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Why I joined OpenAI

from Brendan Gregg's Blog [alt+shift+b] in programming

The staggering and fast-growing cost of AI datacenters is a call for performance engineering like no other in history; it's not just about saving costs – it's about saving the planet. I have joined OpenAI to work on this challenge directly, with an initial focus on ChatGPT performance. The scale is extreme and the growth is mind-boggling. As a leader in datacenter performance, I've realized that performance engineering as we know it may not be enough – I'm thinking of new engineering methods so that we can find bigger optimizations than we have before, and find them faster. It's the opportunity of a lifetime and, unlike in mature environments of scale, it feels as if there are no obstacles – no areas considered too difficult to change. Do anything, do it at scale, and do it today. Why OpenAI exactly? I had talked to industry experts and friends who recommended several companies, especially OpenAI. However, I was still a bit cynical about AI adoption. Like everyone, I was being bombarded with ads by various companies to use AI, but I wondered: was anyone actually using it? Everyday people with everyday uses? One day during a busy period of interviewing, I realized I needed a haircut (as it happened, it was the day before I was due to speak with Sam Altman). Mia the hairstylist got to work, and casually asked what I do for a living. "I'm an Intel fellow, I work on datacenter performance." Silence. Maybe she didn't know what datacenters were or who Intel was. I followed up: "I'm interviewing for a new job to work on AI datacenters." Mia lit up: "Oh, I use ChatGPT all the time!" While she was cutting my hair – which takes a while – she told me about her many uses of ChatGPT. (I, of course, was a captive audience.) She described uses I hadn't thought of, and I realized how ChatGPT was becoming an essential tool for everyone. Just one example: She was worried about a friend who was travelling in a far-away city, with little timezone overlap when they could chat, but she...
6th Feb 2026

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More from Brendan Gregg's Blog

Leaving Intel

InnovatiON 2022 AI Flame Graphs GPU Flame Scope Harshad Sane SREcon APAC Cloud strategy Last day I've resigned from Intel and accepted a new opportunity. If you are an Intel employee, you might have seen my fairly long email that summarized what I did in my 3.5 years. Much of this is public: AI flame graphs and released them as open source GPU subsecond-offset heatmap Worked with Linux distros to enable stack walking Was interviewed by the WSJ about eBPF for security monitoring Provided leadership on the eBPF Technical Steering Committee (BSC) Co-chaired USENIX SREcon APAC 2023 Gave 6 conference keynotes It's still early days for AI flame graphs. Right now when I browse CPU performance case studies on the Internet, I'll often see a CPU flame graph as part of the analysis. We're a long way from that kind of adoption for GPUs (and it doesn't help that our open source version is Intel only), but I think as GPU code becomes more complex, with more layers, the need for AI flame graphs will keep increasing. I also supported cloud computing, participating in 110 customer meetings, and created a company-wide strategy to win back the cloud with 33 specific recommendations, in collaboration with others across 6 organizations. It is some of my best work and features a visual map of interactions between all 19 relevant teams, described by Intel long-timers as the first time they have ever seen such a cross-company map. (This strategy, summarized in a slide deck, is internal only.) I always wish I did more, in any job, but I'm glad to have contributed this much especially given the context: I overlapped with Intel's toughest 3 years in history, and I had a hiring freeze for my first 15 months. My fond memories from Intel include meeting Linus at an Intel event who said "everyone is using fleme graphs these days" (Finnish accent), meeting Pat Gelsinger who knew about my work and introduced me to everyone at an exec all hands, surfing lessons at an Intel Australia and HP offsite (mp4), and meeting Harshad Sane (Intel cloud support engineer) who helped me when I was at Netflix and now has joined Netflix himself -- we've swapped ends of the meeting table. I also enjoyed meeting Intel's hardware fellows and senior fellows who were happy to help me understand processor internals. (Unrelated to Intel, but if you're a Who fan like me, I recently met some other people as well!) My next few years at Intel would have focused on execution of those 33 recommendations, which Intel can continue to do in my absence. Most of my recommendations aren't easy, however, and require accepting change, ELT/CEO approval, and multiple quarters of investment. I won't be there to push them, but other employees can (my CloudTeams strategy is in the inbox of various ELT, and in a shared folder with all my presentations, code, and weekly status reports). This work will hopefully live on and keep making Intel stronger. Good luck.

4th Dec 2025 • 1 votes
Third Stage Engineering

The real performance of any computer hardware in production is the result of the hardware, software, and tuning; the investment and sequence of these efforts can be pictured as a three-stage rocket: I recently presented this embarrassingly simple diagram to Intel's executive leadership, and at the time realized the value of sharing it publicly. The Internet is awash with comparisons about Intel (and other vendors’) product performance based on hardware performance alone, but the performance of software and then tuning can make a huge difference for your particular workload. You need all three stages to reach the greatest, and most competitive, performance. It's obvious why this is important for HW vendors to understand internally – they, like the Internet, can get overly focused on HW alone. But customers need to understand it as well. If a benchmark is comparing TensorFlow performance between HW vendors, was the Intel hardware tested using the Intel Extension for TensorFlow Software, and was it then tuned? The most accurate and realistic evaluation for HW involves selecting the best software and then tuning it, and doing this for all HW options. I spend a lot of time on the final stage, tuning – what I call third-stage engineering. It's composed of roughly four parts: People, training, tools, and capabilities. You need staff, you need them trained to understand performance methodologies and SW and HW internals, they need tools to analyze the system (both observational and experimentals), and finally they need capabilities to tune (tunable parameters, settings, config, code changes, etc.). I see too many HW evaluations that are trying to understand customer performance but are considering HW alone, which is like only testing the first stage of a rocket. This doesn't help vendors or customers. I hope that's what my simple diagram makes obvious: We need all three stages to reach the highest altitude.

16th Nov 2025 • 1 votes
When to Hire a Computer Performance Engineering Team (2025) part 1 of 2

As a leader in computer performance I've been asked by companies about how (and why) to form a performance engineering team, and as this is broadly useful I'll share my advice here. Large tech companies in the US hire performance engineers (under that or other titles) to ensure that infrastructure costs and service latency don't grow too high, and that their service is reliable under peak load. A new performance team can likely find enough optimizations to halve infrastructure spend in their first couple of years, even for companies that have been using commercial performance or observability tools. Performance engineers do much more than those tools, working with development teams and vendors to build, test, debug, tune, and adopt new performance solutions, and to find deep optimizations that those tools can miss. I previously worked on the performance engineering team for Netflix, a large tech consumer running on hundreds of thousands of AWS instances. I'm now doing similar work at Intel (a large tech vendor) for Intel and their customers. As a leader in this space I've also interacted with other performance teams and staff doing performance work at many companies. In this post I'll explain what these teams do and when you should consider forming one. In part 2 I'll provide sample job descriptions, specialties, advice, pitfalls, comments on AI, and what to do if you can't hire a performance team. It's easy for hardware vendors like Intel to justify hiring performance engineers, as the number one factor in sales is beating a competitor's performance. However, my focus in this post is on non-vendor tech-heavy companies who hire these staff to drive down costs and latency outliers (e.g., banks, telecomms, defense, AI, tech-based companies, and anyone else who is spending more than $1M/year on back-end compute and AI). What is the ROI of performance engineering? The main ROIs are infrastructure cost savings, latency reductions, improved scalability and reliability, and faster engineering. The cost savings alone can justify a performance team and can help calculate its size, and I'll explore that in depth, but the other ROIs are worth considering and may be more important to a company depending on its stage of growth. Infrastructure Cost Savings and Margin Improvements An appropriately-sized performance team should be targeting 5-10% cost savings per year through tuning and product adoptions. (I'll explain appropriate sizes in the When To Hire section.) For many large companies a 5% result would be considered "good" and a 10% would be "great." Achieving this in practice can mean finding large wins (15-80%) on parts of the infrastructure, which become 5-10% overall. Wins are cumulative, so a team hitting 5% savings each year will multiply to become 28% after their 5th year (like compound interest). Even a modest 2% per year will become significant over time. While these compounded numbers can become large, a team needs to continue finding new cost savings each year to justify long-term retention, and should always focused on the next 5-10%. Companies may invest in this work for more than just the cost savings: It can be about developing a competitive advantage in their area by providing a better cost/performance ratio, especially for companies with similar tech-based services that pass costs on to customers. For sites that haven't employed performance engineers before, there can be enough low-hanging fruit that the team can halve infrastructure costs in their first couple of years (50%). It all depends on the number of staff, their level of expertise, how much perf work other staff are already doing (senior developers, SREs), how much custom code is running, and how complex and volatile the stack is. It would great if we could publicly share specific results, which would look something like this: "This year we helped reduce our company's infrastructure spend by 5%, from $60M/year to $57M/year, however, since our user base also grew by 3%, we actually reduced cost-per-user by 8%, saving $5M/year in this and all future years." However, these numbers are usually considered financially sensitive as they can reveal company growth, financial health, confidential infrastructure discounts, etc. As a performance engineer I can talk publicly about percent wins on a back-end service, but I usually can't map it to dollar signs. That doesn't help other companies to understand the value of performance engineering. It's not so much of a problem in Silicon Valley, since staff change companies all the time and word spreads about the latest practices in tech. But in far away countries performance engineering doesn't really exist yet, even though there are companies with sufficiently large infrastructure spend. Continuing the above example, a typical 8% win could be composed of: 2%: direct optimizations. We looked across all the infrastructure and found on average 5% wins on 40% of the infrastructure (on the rest we found nothing, this year). 3%: developer/SRE enablement. We developed and adopted custom observability tools and helped developers use them, who in turn found some 15% wins across 20% of our infrastructure. 3%: vendor adoptions. We supported a major adoption project that replaced 10% of our infrastructure for a 30% win. With developer/SRE enablement and vendor adoptions, the performance team isn't finding the wins directly but is enabling other teams and vendors to do so. For example, when I worked at Netflix we built and maintained the flame graph "self-service" application, which developers used daily to find wins, and we worked on multiple product adoptions every year. This all needs to be considered as part of the performance team’s ROI. Latency Reductions Reducing the response time or latency of a service is a large part of performance engineering. This involves analyzing average latency, 99th percentile latency, and outlier latency; ensuring latency SLA/SLOs are met; and ensuring acceptable latency during perturbations or peak usage. Many of the cost optimizations described earlier will also reduce average latency, but latency variance or outliers can remain. For example, a once-every-5-minute system task may have negligible cost and CPU footprint, but it may briefly perturb the application and cause latency outliers. These are debugged differently, often using monitoring, logs, distributed tracing, system-level tracing, packet logs, and custom ad-hoc tools. Sometimes the high latency is caused by the request type itself (the system is fine, but the end-user has requested a slow thing) or is an expected consequence of load (queueing theory, tail latency). Other times it can be from complex interactions across multiple layers of the software stack or from interactions across multiple network endpoints. As a related aside: One performance anti-pattern is when a company, to debug one performance problem, installs a monitoring tool that periodically does work and causes application latency outliers. Now the company has two problems. Tip: try turning off all monitoring agents and see if the problem goes away. While latency is the main consideration to improve end user experience, others include throughput and parallelism. Improved Scalability and Reliability Systems under load can respond with exponential latency or a cascading failure, causing disruptions or a service outage. Performance engineers can test resource scalability with custom load generators and benchmarks, and use analysis tools to study all parts of the system to find and solve bottlenecks. A performance engineer will not just measure scalability limits, but should also explain what the limiting factors are and how to address them to scale further. A stable and performant service will also earn trust in your company, and can help you grow customers more quickly. It may be a requirement for satisfying enterprise SLA/SLOs. I'll share a scalability story from my time at Sun Microsystems (a vendor). My goal was to achieve the number one throughput in the industry for a storage system, which would require exceeding 1M IOPS. The expected bottleneck was the rotational disks. I developed my own load generators and analysis tools and concluded that the real bottleneck was, surprisingly, the CPU interconnect. The interconnect was AMD HyperTransport 1, so AMD sent me a new systemboard with HT3 and faster CPUs. I installed it and…performance was identical. I was upset with myself for getting it wrong, until I discovered that AMD had sent me a HT1 board by mistake. They then sent me a real HT3 board and the performance increased by up to 75%! The CPU interconnect (when present) is just one of many components that companies typically don't check, and commercial observability tools don't check either. Faster Engineering Performance engineers can take care of components outside of a developer's code base so the developers can stay focused, and also provide them with a greater performance budget so that they can adopt expensive features earlier. For some early stage companies this ROI may be their most important (and is sometimes called engineering velocity). In detail: Eliminate outside performance distractions: A development team can be coding at one hundred miles an hour in their codebase, but then run into a performance problem in a library, kernel, hypervisor, or hardware component, and need to slow down to learn some new thing and its analysis tools. Or, it could be some new performance technology that someone saw on hackernews and the development team wonder if they should stop to evaluate it. These performance activities can be offloaded to the perf team, so the developers stay focused on their code and at full speed. This is the same as how OS, deployment, and reliability issues can be offloaded to SRE and DevOps teams. Bypass expensive project failures: Good performance engineers know the internals of the software and hardware stack (including the Linux kernel). Many developers don't and most of the time they don't need to. But this can lead to developers proposing ideas based on incorrect assumptions. (This actually happens a lot.) Having a one hour meeting with a performance engineering team can save months of engineering effort: A developer talks about their ideas A and B, and the perf team says "A won't work and this is why, but B sounds good and we can help." Months saved in one hour. At one large tech company many years ago I analyzed an engineering proposal to adopt a new event-based coding framework on the belief it would improve performance by ten fold. My analysis showed the real gain would have been less than 10%. The project was abandoned. This saved having all the engineers rewrite all the company's code, something we were expecting would take a year. This is one of the biggest performance wins of my career, not measured as a percentage but rather as engineering hours saved. Develop accelerator tools: As mentioned earlier, performance teams can develop custom observability tools that developers use, finding issues sooner and accelerating development. For example, I've been publishing here about AI flame graphs, which involved kernel and hardware internals to build. Faster feature adoption: Reducing costs and latency can enable developers to do more with a limited infrastructure and latency budget, offering more capabilities for their service or allowing more processing to be crammed in per request. Some companies have cost limits for adding features, so optimization work can mean a feature is now approved. All this work can mean a company can outpace their competitors with feature adoption, while maintaining a reliable, low-latency, cost/performance competitive service. What do performance engineers do? For non-vendor tech companies, in summary: A. Test, debug, and tune new software and hardware products to find performance improvements, and drives company-wide adoption. Examples: New cloud instance types, language runtimes, JVM versions, JVM subsystems (new GC algorithms or compilers: Graal vs c2), system libraries (glibc vs tcmalloc etc.), kernels (Linux vs BSD) and versions, compilers (gcc, llvm, icc), processor features (AVX, QAT, etc.), hardware accelerators, and so on. It can take months to debug, fix, and patch everything so the latest thing delivers its performance claim. B. Develop in-house performance solutions, such as custom analysis tools, that other teams use to find performance wins. Examples: Custom monitoring using Prometheus and Grafana, one-click flame graphs, and analysis tools using eBPF: All of this is open-source based, but someone has to get it working locally, integrate them with existing local tools, teach other teams how to use them, and maintain them. C. Does deep-dive analysis to identify and reduce workload bottleneck(s) and latency outliers. Examples: Using code profilers (CPU flame graphs), distributed tracers (OpenTelemetry and products), application logs, system counters (Linux: sysstat), system tracers (Linux: eBPF, Ftrace, perf), static and dynamic instrumentation (Linux: kprobes, uprobes), debuggers (gdb, etc.), hardware counters (Linux: perf), and on rare occasions hardware instruction tracing. A lot of hands-on live debugging over an SSH session, following methodologies to efficiently find the root-cause(s), which can require the development of custom tools (mini load generators, observability tools, etc.). D. Optimize software and hardware via tunable parameters and configuration choices. Examples: System tunables (Linux: sysctls), network tunables (socket options, qdiscs), device tunables, runtime tunables (Java -XX:*), library settings, environment variables, etc. As with (C), the team needs SSH access to do this and likely superuser privileges. E. Work with development teams (internal and external) to catch non-scalable solutions early in development, and to suggest or test later performance improvements. Examples: Identifying communication layer will flood network links when horizontally scaled; A developer has a good optimization idea but can't get it to work and needs some help; There's a performance-related pull request on some software the company uses but the request is two years old and needs someone to fix code conflicts, test it, and advocate for merging it. F. Develop proof-of-concept demonstrations of new performance technologies. Examples: Linux eBPF and io_uring can provide significant performance improvements when developed into hot-path kernel-based accelerators, but someone needs to at least build a POC to show it would work for the company. These are typically too esoteric for developers to try on their own. G. Develop performance improvements directly for internal and external code. Examples: Performance engineers get a lot done by asking the right people, but sometimes no one has the time to code that Linux/runtime/database performance fix the company needs, so a perf engineer takes it on. We aren't as quick as full-time developers since we are hopping between different languages all the time, and as a new code base committer will typically come under extra (and time-consuming) scrutiny. H. Capacity planning activities: purchase guidance, choosing metrics to monitor, and bottleneck forecasting. Examples: Modeling and performance characterization for hardware purchases, resource utilization monitoring to forecast capacity issues (nowadays often done by developers and SREs using monitoring tools); propose the best metrics to be watched in those monitoring tools for alert generation and auto-scaling rules; work with business side of the company to help define practical SLA/SLOs. I. Perform knowledge sharing to uplift engineering. Examples: Performance education to help developers produce more efficient software; act as a conduit to share performance learnings between teams (that may otherwise be siloed) to avoid rework and rediscovery. J. Provide in-house expertise to guide purchasing performance solutions. Examples: Providing in-house expertise for performance topics like observability, telemetry, and eBPF can help the company choose better commercial products by evaluating their capabilities and overhead costs, and can recognize which are just Prometheus and Grafana, or my open source eBPF tools, in a suit. Without expertise you're vulnerable to being ripped off, or may adopt a tool that increases infrastructure costs more than the gains it provides (I've seen some that have overhead exceeding 10%). To elaborate on (A), the testing of new products: Other staff will try a technology by configuring it based on the README, run a load test, and then share the result with management. Some companies hire dedicated staff for this called "performance testers." Performance engineers get more out of the same technology by running analyzers during the test to understand its limiter ("active benchmarking"), and will tune the technology to get an extra 5%, 50%, or more performance. They may also discover that the limiter is an unintended target (e.g., accidentally testing a caching layer instead). Any performance test should be accompanied by an explanation of the limiting factor, since no explanation will reveal the test wasn't analyzed and the result may be bogus. You can simply ask "why is the result not double?". As an aside: "CPU bound" isn't an explanation. Do you mean (a) clockspeed, (b) thread pool size, (c) core count, (d) memory bus (which kernels misleadingly include in %CPU counters), or something else (like power, thermal, CPU subsystem bottleneck)? Each of those leads to a different actionable item for the company (E.g.: (a) faster processors; (b) more threads; (c) more cores; (d) faster memory, bigger caches, less NUMA, or software techniques like zero copy). That's just the generic stuff. The code behind any CPU bound workload will also be analyzed to look for inefficiencies, and sometimes their instructions as well. Day to day, a performance engineer can spend a lot of time fixing broken builds and configuring workloads, because you're the first person testing new patches and bleeding-edge software versions. What I've described here is for companies that consume tech. For vendors that sell it, performance engineering includes design modeling, analysis of prototype and in-development software and hardware, competitive benchmarking, non-regression testing of new product releases, and pre- and post-sales performance analysis support. (I explain this in more detail in Systems Performance 2nd edition, chapter 1.) When to Hire a Performance Team and How Many Most companies I've encountered are already doing some kind of performance work scattered across projects and individuals, but they don't yet have a central performance engineering team looking deeply at everything. This leaves their attention spotty, ok in some areas, poor to absent in others. A central performance team looks at everything and prioritizes work based on the potential ROI. Here are a few rough rules to determine when you should start forming a company-wide performance engineering team and how to size it (see caveats at the end): (A) One engineer at $1M/year infrastructure spend, then one per $10M to $20M/year That first engineer finds some of the low-hanging fruit, and should be cost effective as your company grows past $1M/year. I'd then consider another performance engineer for every $10M to $20M, and maintain a 3:1 junior:senior ratio. The values you use depend on your performance engineer's skill and the complexity of your environment, and how aggressively you wish to improve performance. At a $20M spend, 5% yearly wins means $1M in savings per staff member (minus their cost); whereas for a $10M spend you'd need to hit 10% wins yearly for $1M in savings. Consider that as your spend keeps growing you will keep adding more staff, which makes their job harder as there is less low-hanging fruit to find. However, your site will also be growing in scale and complexity, and developing new performance issues for the growing team to solve. Also, smaller percent wins become more impactful at large scale, so I expect such a growing perf team to remain cost effective. (To a point: the largest teams I've seen stop at around 150 staff.) (B) Staff spend should equal or exceed observability monitoring spend If you're spending $1M/year on an observability product, you can spend $1M/year on a performance engineering team: e.g., 3 to 4 good staff. If you're only spending $50k/year on an observability product, you can't hire a performance engineer at that price, but you can bring in a consultant or pay for performance training and conference attendance. As I'd expect staff to halve infrastructure costs over time, just the savings on monitoring alone (which typically scale with instance/server count) will pay for the new staff. Because these new engineers are actively reducing infrastructure spend, the total savings are much greater. (C) When latency or reliability is prohibitive to growth I’ve heard some small companies and startups say they spend more money on coffee than they do back-end compute, and don't want to waste limited developer time on negligible cost reductions. However, when a wave of new customers arrive they may hit scalability issues and start losing customers because latency is too high or reliability is too inconsistent. That's usually a good time for small companies to start investing in performance engineering. Caveats for A-C You likely already have some perf engineers under different titles, such as senior developers or SREs who are focusing on perf work, leaving less work for the central performance team. Account for these focused staff when you are determining how many performance engineers to hire. There will be a backpressure effect: If a new team halves your infrastructure, do you then halve the team? Up to you. But first think about what a perf engineer does: They have to work on anything, any operating system, language, or hardware the company needs. So you have these extra staff that can go deep on anything. Just some personal examples: There was an 18 month stretch when Netflix needed more core SREs on rotation, so myself and other perf engineers were temporarily assigned to do SRE work; Netflix would also have me do kernel crash dump analysis and application core dump analysis, since I was already using debuggers at that level. You ideally have more performance engineers than technologies so staff members can specialize. E.g.: If your stack is AWS, Intel, Linux kernel, Ubuntu OS, containers, lambda, gRPC, Java, golang, Python, Cassandra, and TensorFlow, that's 12 performance engineers. Plus at least one for locally developed code. Want to go multi-cloud? Add another engineer for each CSP. Remember that performance wins are cumulative for future years. A novice team could struggle to get up to speed with both performance engineering and your complex environment, and could also discover that you already had senior staff find all the low-hanging fruit. They might therefore only deliver 2% cost savings in each of their first three years. But that still combines to be 6% going forward. Companies and Global Staff Here are some example articles about performance engineering work at non-vendor companies: Netflix: Cloud Performance Root Cause Analysis [me, 2018] Meta: Strobelight: A profiling service built on open source technology [Jordan Rome, 2025] Pinterest: Debugging the One-in-a-Million Failure: Migrating Pinterest’s Search Infrastructure to Kubernetes [Samson Hu, et al. 2025] LinkedIn: Who moved my 99th percentile latency? [Richard Hsu, Cuong Tran, 2015] eBay: Speed by a Thousand Cuts [Senthil Padmanabhan, 2020] Twitter: #ExpandTheEdge: Making Twitter Faster [Todd Segal, Anthony Roberts, 2019] Salesforce: How Salesforce makes performance engineering work at Enterprise Scale [Archana Sethuraman] Uber: PerfInsights: Detecting Performance Optimization Opportunities in Go Code using Generative AI [Lavanya Verma, Ryan Hang, Sung Whang, Joseph Wang] Twitch: Go’s march to low-latency GC [Rhys Hiltner, 2016] Airbnb: Creating Airbnb’s Page Performance Score [Andrew Scheuermann, 2021] Stripe: Using ML to detect and respond to performance degradations in slices of Stripe payments [Lakshmi Narayan, Lakshmi Narayan, 2025] DoorDash: How DoorDash Standardized and Improved Microservices Caching [Lev Neiman, Jason Fan, 2023] Roblox: How We Redesigned a Highly Scaled Data Store to Lower 99th Percentile Latency 100x [Andrew Korytko, 2020] Capital One: Driving cloud value through cost optimization & efficiency [Jerzy Grzywinski, Brent Segner, 2024] I would like to add Bank of America, Wells Fargo, JPMorgan Chase, and CitiGroup to this list since they have many staff with the title "performance engineer" (as you can find on LinkedIn) but it's hard to find public articles about their work. I'd also like a canonical list of central performance engineering teams, but such org chart data can also be hard to find online, and staff don't always call themselves "performance engineers." Other keywords to look out for are: insights, monitoring, and observability; some are just called "support engineers". Note that there is also a lot of performance engineering done at hardware, software, and cloud vendors (Intel, AMD, NVIDIA, Apple, Microsoft, Google, Amazon, etc.) not listed here, as well as at performance solution companies. In this post I just wanted to focus on non-vendor companies. Global Staff I've never seen concrete data on how many people are employed worldwide in performance engineering. Here are my guesses: Staff identifying as performance engineers at non-vendor companies: <1,000. Staff identifying as performance engineers at SW/HW vendors: >10,000. Staff who have become focused on performance engineering work under other titles (developer, SRE, support): >100,000. Staff who occasionally do performance engineering work: I'd guess most developers. It's possible LinkedIn can provide better estimates if you have enterprise access. Conclusion There are many reasons to hire a performance engineering team, such as infrastructure cost savings, latency reductions, improved scalability and reliability, and faster engineering. Cost savings alone can justify hiring a team, because a team should be targeting a cost reduction of 5-10% every year, which over the years adds up to become significantly larger: 28%-61% savings after 5 years. In this post I explained what performance engineers do and provided some suggested rules on hiring: A) One engineer at >$1M infrastructure spend, then another for every $10-20M. Note that you likely already have some senior developers or SREs who are focusing on perf work, reducing the number of new performance engineers you need. I've met people who would like to work as performance engineers but their employer has no such roles (other than performance testing: not the same thing) despite spending millions per year on infrastructure. I hope this blog post helps companies understand the value of performance engineering and understand when and how many staff to hire. Hiring good performance engineers isn't easy as it's a specialized area with a limited talent pool. In part 2 I'll discuss how to hire or train a performance engineering team and provide sample job descriptions and tips, and what to do if you can't hire a performance team. Thanks Thanks for the feedback and suggestions: Vadim Filanovsky (OpenAI), Jason Koch (Netflix), Ambud Sharma (Pinterest), Harshad Sane (Netflix), Ed Hunter, Deirdre Straughan.

3rd Aug 2025 • 1 votes
3 Years of Extremely Remote Work

In the last 3 years I've attended 77 meetings that began between 1am and 6am, roughly once every two weeks, followed by my usual 7am start, Monday to Saturday. I'm working remotely from Australia for a US firm (Intel) who does not have a local office here. I'm not complaining. I work weird hours, but I don't think I work too many. I'm writing this post because there are some misconceptions and assumptions about the lives of remote workers, and I thought I'd share my own details as an anecdote, along with some tips for others in a similar situation (US job from Asia). Most early meetings were 1 hour, but some were longer, for a total of 102 hours awake. As a histogram: I've never been a morning person, but I can manage a 7am start. What about a 2am meeting? Also doable. They sound ok in isolation, but consider that every 2-3am is followed by a 7am start, which means a 6:30am alarm after going back to sleep at 3:30am, if you're lucky. It's not easy working this timezone difference, and I'd guess others have it even worse than I do (more meetings). Like other remote staff I work with, I have a dedicated office at home where I can close the door and work uninterrupted for hours (it's changed quite a bit since it was filmed in the eBPF documentary): That's a Samson Meteor mic on a desktop suspension boom, and I have another suspension boom clamped onto a bookcase holding a Logitech BRIO camera (when I had it sitting on my monitor it'd shake as I typed). It's important to have the best sound and video when that's how you're interacting with people all day. Miscellaneous notes and tips about remote work: Count out-of-hours meetings. Sometimes people hesitate to book me at 2am, when there's no other time that would work, and it takes a few emails to convince them that it's ok. I've found it saves time to log these meetings, count them, and share stats: "I've had 76 meetings between 1am and 6am, if you need to add another, that's ok, it'll be my 77th." Never complain about the hours. There may be someone in management who doesn't support remote work, who could use such complains to argue against it. Sometimes, when I'm searching to find the right words to say at 4-something-am, I've confessed that I'm a bit tired, but I really try to never mention it. Staying motivated. I found keeping a daily log of what I accomplished works best (I've done this for over a decade). If one day my entry looks soft, I try to do more on the next. I summarize each week for my manager. People assume it's a problem when it isn't. Brendan didn't accept the meeting, oh, it's because it's 2am for him and he'll be asleep. Wrong! It's because I have a clash with another 2am meeting. I try to communicate this with the meeting host, but there can be others in the meeting that don't get the message, and they never consider this possibility. If I were back in California I'd still miss the meeting, but people would assume it's due to a clash. Here, they assume I'm asleep and not making the effort, when in fact I am. It means people are assuming that remote work is a problem when it isn't. Some meetings get cancelled or silently recorded. The 77 count I mentioned earlier doesn't include the several meetings that were cancelled at the last minute, but I woke up for anyway, or those that weren't supposed to be recorded but I woke up to find they were. If you have remote staff, please try to cancel meetings before they go to bed, and be clear on which meetings are recorded for later viewing. Upset stomaches. One early meeting every two weeks doesn't sound too bad. The worst problem is that it can leave me with an upset stomach that can last for days. I'm still working fine, it's just uncomfortable. I don't know if other people suffer this or why it happens. Maybe it's just the extra coffee. Fewer sick days. I don't normally take many sick days, so I can't say my data is very significant. FWIW: In my last in-person job I averaged 1.5 sick days/year (9 in 6 years), and now it's 0.33 (1 in 3 years). Northen/Southern hemisphere times get weird. Daylight savings moves in different directions and on different dates, so from Sydney depending on the time of year I have 3, 4, or 5 hours of overlap with 9-5pm on the US west coast. To make it easy for people I setup my calendar with my work hours highlighted. Saturday? Saturday morning is Friday afternoon in the US. For a while I tried working Tuesday to Saturday, but it's better for family time if I finish early on Saturday (at US 5pm) and work Monday to make up the difference. Phone alarms Career limiting I've experienced it to be career limiting, and I've heard the saying "out of sight, out of mind." Opportunities can be given to local workers despite the remote worker being more qualified, or even number one in the world in that area. The remote worker is then expected to teach the local worker in weekly or monthly meetings. It's not enough time and there's a power imbalance: the local worker is in charge and doesn't have to listen. This reduces company competitiveness. It's also fixable: try giving remote workers the chance they are best qualified to do. Compared to office work. It depends on the job and meeting load. In my last years as an in-person office worker I was on a team where we typically worked solo on different projects, with headphones on, and primarily communicated over chatrooms with few in-person meetings. The only regular time we had human interaction was lunch. Remote work has not been a big difference to that kind of job: similar work, similar chatrooms. (The thing I miss the most about the office is playing cricket with other staff after work.) It wouldn't make a big difference to my current job either, as the people I work with are scattered. The one thing it would solve is "out of sight" problem, but that's not the only way to solve it. Remote work success stories. Linux development is a great example of engineers around the world working together. Note that Linux engineers do try to meet at least once a year at one of the Linux conferences, something remote office workers can do as well at company get-togethers. My books are another example: they are out-of-hours projects where I worked with the reviewers online, some of whom I still haven't met. And the world's first AI Flame Graphs is the work of a fully-remote team. I was in a video meeting recently with US staff where I mentioned the "77 meetings between 1 and 6am" statistic, and I could see the look of shock in their faces. Did they assume I was just working 9-5 and not making an effort to accommodate other timezones? I know some companies are discussing ending remote-work: are the deciders also making such assumptions about the lives of remote workers? It may not do much, but I can at least share my own details here as an example anecdote. Update: Some comments about this post have pointed out that these hours can be unhealthy and shouldn't be encouraged, and I don't disagree. I hope to have fewer early meetings in the years ahead, myself. This post is just to show that remote workers can be more accomodating than people may assume, and I hope that's taken into consideration when changing remote work policies. When some people hear I'm working from Australia, they may think of beaches and surfboards and sunny vacations, but my reality is a full time job across weird hours, lots of coffee, and being overlooked for opportunities. That said, every job has its pros and cons, and I'm still grateful that some companies make fully remote work an option.

21st May 2025 • 1 votes

More in programming

Contract testing implementation challenges

This post was previously published through my newsletter on October 19, 2026. From time to time, I will republish newsletter issues on my blog here if I think people (and search engines) might benefit from it. If you want to read everything I’ve written once it is posted, I recommend signing up for the newsletter. For the last 5-6 years or so, I’ve been talking about, teaching and helping teams implement contract testing on a regular basis. To make that more concrete: at the moment, I’m having ongoing conversations with four different potential clients about helping them in some way with their contract testing implementation, and so far, I’ve run my contract testing workshop four times this year. It probably doesn’t come as a surprise to you when I say that I really like the concept of contract testing as a means of addressing integration testing challenges in distributed software systems. However, no matter if I’m speaking, teaching or implementing contract testing, certain challenges almost always come up at some point, and I want to highlight some of those today. Understanding the concept of contract testing First of all, it often takes people a while to understand the concept of contract testing, especially when they’re used to what I call the ‘traditional’ approach to integration testing: deploying the systems and services in scope to a shared testing environment and then testing them ‘as a whole’. Of course, the more distributed your system and your development process is, and the higher the deployment frequency, the more complex and the slower this integration testing approach is going to be. The premise behind contract testing is to break that integration testing puzzle down into small chunks of individual consumer-provider pairs, and then test the integration between those two in an asynchronous manner. By asynchronous, I mean that there is no need to deploy consumer and provider into a shared environment; both parties perform their part of the process in their own, local development environment. This means you can detect potential integration issues before you deploy, instead of stumbling onto them after you do so. This makes contract testing (or contract-based integration testing, to use its proper name) a significantly different approach to integration testing compared to the more ‘traditional’ approach. In my experience, it usually takes people time to wrap their head around how the process actually works, which steps you should take and in which order, and what you (do not yet) know after each step. It often takes going through several contract testing cycles before people start to ‘get it’. That’s not their fault, that is to be expected, since the contract-based approach to integration testing is, again, quite different from what they’ve been doing for so long. To better cater to this, I redesigned my contract testing workshop a year and a half or so ago. It is now a full-day workshop (half a day is simply too short), and I take much smaller steps and repeat them more often. From what I see, this has led to a better understanding of the concepts with my audience, and that’s the whole point. Contract testing === Pact I’ve talked to quite a few teams that had heard of contract testing somewhere, decided that that was the way out of their integration testing problems, and then immediately started writing contract tests with Pact. Understandable, because Pact is a very useful, very powerful and very popular tool, plus, it’s open source, which makes it easy for teams to get started. Often, they skipped a step in the process. Pact is very much a consumer-driven contract testing tool by nature, and while consumer-driven contract testing is the richest and most powerful of the different approaches to contract testing, it is not necessarily the best fit for every team and every context. It’s a classic example of using the wrong tool for the problem at hand, because they didn’t take enough time looking at the problem and the available solutions. That’s not the problem of Pact, even though it is often framed that way (‘Pact didn’t solve my problems, therefore Pact is not a good tool’). That’s a ‘we didn’t fully understand the problem and the context’ problem. Contract testing removes the need for communication Another challenge that I often see when I talk about or help teams with contract testing is the fact that teams don’t talk to each other. This then leads to integration issues, because team A expects something from team B that team B doesn’t supply. Contract testing is not the solution to these problems. It can’t be - tools alone do not solve problems, let alone communication problems. What contract testing does do is make potential integration issues visible early on in the development process, often earlier than (again) more ‘traditional’ approaches to integration testing. That’s where the value of contract testing can be found. It is not a means to replace communication between teams. In fact, and this is especially true for consumer-driven contract testing, contract testing cannot succeed without good communication between consumer and provider teams. Contract testing replaces all other types of integration testing This one comes up less often than it used to, but sometimes, I still hear people saying that when they will have contract-based integration tests in place, they don’t need other types of integration tests anymore - including E2E tests. That’s simply not true. While contract testing is a great way to find out earlier about the impact of a change in a specific consumer or provider further downstream, in many cases, I wouldn’t rely on these tests alone before moving to production. Because of its asynchronous nature, contract-based integration testing only verifies whether a consumer and a provider speak the same language - can a consumer understand the message returned by a provider in a specific situation? It does not verify that the request or the response message reaches the other party in the first place, for example. In other words, it doesn’t test connectivity between a consumer and a provider. And because integration testing is broken down into individual consumer-provider pairs, you don’t see the entire system working ‘as a whole’. This means you might want to keep a few end-to-end tests in place, even when you’ve got good contract testing coverage across the board. The above is not a complete list of challenges with contract testing, but the ones I mentioned here are those that come up most often.

22 hours ago • 1 votes
Suffering as a Feature

Have you seen this? If you haven't, you should. I think everyone needs to. Wealth inequality on a scale this extreme is almost impossible to explain. You have to experience it to understand. Go ahead. Try it out. Where is the top of this graph? Good question. Keep

yesterday • 1 votes
The upvote dilemma

Hiding upvotes on the discovery feed

2 days ago • 2 votes
The slopocalypse survival guide

Slop is without a doubt everywhere. Be it in restaurant’s menus, music playlists, or online game storefronts, it is now impossible to escape it. Yet, I’ve never met anyone who was actually looking forward to consuming that. No matter how hard it’s shoved down our throats, the human longing to connect with other people through art still remains. Raymond Kotewicz They will not let you filter A simple solution would be to have slop filters. Automatically label AI-generated trash, and let users hide it if they don’t want to see it. So far, I don’t think any of the major internet platforms has implemented this. The common excuse for why they don’t let you easily filter out slop is that it would be technically too difficult. Let me be clear with everyone here: this is complete bullshit. We’re talking about companies that can hire some of the most talented engineers in the world. I don’t think anyone seriously believes they can’t come up with a way to guess if a file has been generated by AI or not. 90% of the slop out there stands out so much everyone can see how it was made after looking at it for 5 seconds. A more plausible reason for the lack of slop filter is that they are simply testing out the waters. They are checking if users will tolerate it. The question tech executives want answered is: will people buy this garbage? And if the answer to that question is yes, here’s what they will do: they will start generating it themselves. They don’t need the useless meat proxies who think typing ten words and pressing enter makes them creative. They definitely don’t want to verse anyone royalties when they could just be making a one time purchase of tokens. If you think this is not real, just ask Tim Sweeney. I bet he will be more than happy to confirm. Roman Navarro Curation by humans for humans So now that it’s clear that tech companies will not save us from drowning in slop, it’s time to turn back to actual humans instead. The good news is they are a lot of people who are here to help you. There are thousands of people on the internet who will search through mountains of content to find the perfect piece of art they want to share with the world. We don’t explicitly call them curators. They are streamers, bloggers, journalists, DJs, overly enthusiast fans, or simply your friends. Some of those people are seriously amazing. There are DJs out there who will spend thousands of hours digging through crates to craft you the perfect ninety minutes of music. Why do you still need those machine-generated playlists? The alternative to blindly trusting the output of a recommendation algorithm isn’t always to become an expert in every field of art. Sometimes you just have to put the trust you had in a machine back into another person. Back to the real world? The real long term solution would be to stop relying only on the internet for distribution. This is already a thing in the music industry. Every city has a record shop that will sell you a carefully selected set of vinyls. For many musicians, physical sales (and concerts) are a much better source of income than streaming. The same goes for the movie. While text-to-video AI is a thing, the real money isn’t made by generating 30 second TikTok dramas. The real money comes from people paying tickets to see a full-length movie in a theater. Sadly I’m not too optimistic about my own field: video games. Somehow it seems the direction we’ve taken is the opposite. We’re all in on online distributions platforms. We have fully accepted them as our new digital overlords. Next month GTA V is coming out without a disk in the box. Sony already announced that the next Playstation will not support physical media. Physical distribution is not even mentioned in the pitch of the average indie publisher. In Breda, the small Dutch city where I live, we used to have two dedicated video games shop. Higher interests rates, expensive rents, and various policy failures have done their jobs: they are both closed. I don’t think this is a good sign for the survivability of the gaming industry.

2 days ago • 2 votes
LARPing with Agents (and Why It Works)

Understanding how assigning anthropomorphic traits to agents can improve their effectiveness and interaction.

2 days ago • 1 votes
📚 BoredReading

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