Recent content on Lalit Maganti
To get promoted as a software engineer in Big Tech, you generally need to show “ownership” of a product or area. This means being responsible for it and deciding what should happen over time. I often hear more junior engineers ask: “How can I demonstrate ownership when my manager hasn’t given me anything to own?” This way of thinking is a trap: an easy one to fall into, but a trap nonetheless. The…
In Devtools must be open source1 (via), David Crawshaw makes the case that, because of coding agents, we’re now in an era where devtools will be personalized by individual users. Specifically, agents’ ability to jump into new codebases and build whatever we want means we’ll be hacking on the source of the devtools we use day to day (even those without extension APIs) adding features and…
Codeberg, a Git code hosting platform, recently took a decision to prohibit projects that mostly consist of generative-AI-written code which has prompted concern and extensive discussion elsewhere. The decision does not surprise me, and I don’t mean that as a criticism. Codeberg has always presented itself as a mission-driven alternative to GitHub, not neutral infrastructure.1 What interests me is…
Antirez, the creator of Redis, recently argued that expert programmers using AI should think of themselves as being Linus Torvalds. The key part of his analogy is this: Automatic programming, instead, in the hands of people that are expert technicians, or expert programmers, expert designers, expert software architects, is to assume the role of Linus, with the agents and the LLMs assuming the role…
Note: this post was revised after publishing for increased clarity, based on reader feedback. “How do you find problems worth working on?” a senior engineer I mentor asked me recently. He’s trying to make the jump to staff engineer and realized that the role isn’t just about doing the work he’s assigned. He also needs to get involved in figuring out what his team and org should be building.…
Writing for the world is something which has ebbed and flowed for me over time. I’ve always liked sharing my thoughts, starting with websites all the way back when I was a kid. In times when I sustained it, I had various “blog”-like things for technical projects which would often veer into sharing personal beliefs as well. It’s been a year since my latest attempt at what I expect to be a lifelong…
Working with lots of changes in parallel on git can be painful. You end up juggling branches and commits, and running scary rebase -i commands that can leave your tree in a half-broken state if you so much as sneeze. jj, an alternative to git, gets discussed a lot these days (1, 2, 3, 4) and is often pitched as a solution. While I’m very sold on the problems jj is trying to solve, the way it…
We just released Perfetto v57 and I wanted to share the new things I’m most excited about. This is something I wanted to do for past releases but I just never quite got round to it. It’s also something I plan on doing more of going forward: there might even be dedicated pieces if I think the feature deserves it! PyTorch traces reliably work!# What I’m most excited about in this release isn’t a…
When impressive performance gains do not matter is a very nice article covering some ways in which going after performance alone is not sufficient without considering the wider picture. It resonated a lot with how I think about performance. If there are multiple bottlenecks in the pipeline—and with these systems, this is common—the overall throughput will not improve until every last bottleneck is…
Since my original launch post for syntaqlite, I’ve been quietly working away on it in the background. A lot of the work has been fixing correctness bugs which I discovered as I integrated it into production as the parser for PerfettoSQL in the Perfetto trace processor: as I wrote previously, this has been my dream for over 8 years so it’s amazing to see it finally realized. Just today, I released…
I came across Iroh (via, via) today as it hit 1.0 and found it a really interesting solution to a problem I knew existed but had not thought a lot about. Judging from the comment sections, it seems pretty clear that lots of people are confused as to exactly what Iroh is. I don’t think their launch post does their product justice at all, and their tagline is “IP addresses break, dial keys instead”…
This post was formerly titled “17 bugs in 10 weeks from AI security scanning”. It was changed upon feedback from trusted readers who suggested, while accurate, it did not give a good sense of what I’m actually arguing in the post. Over the last several weeks, I’ve been receiving more security bug reports for Perfetto’s trace processor than I ever have before, all of them found by AI. And I’m very…
Eurovision was on yesterday. I’ve never been interested much in the musical side but the weird political dynamics of Eurovision voting have always fascinated me; I tune in each year just for them and somewhat snarky commentary of Graham Norton, the UK commentator. As I was watching the jury votes come in, a question popped into my head: Which country has voted the best in Eurovision? That is,…
In my work on Perfetto, a performance debugging tool, one question I get often is: “how do I split a Perfetto trace into multiple files?” Instead of answering directly, I say: “there isn’t an easy way to do that, but what’s leading you to collect traces large enough to want to split?” This is one of my golden rules at work. When a user asks me something “weird”: don’t answer the first version of…
For eight years, I’ve wanted a high-quality set of devtools for working with SQLite. Given how important SQLite is to the industry1, I’ve long been puzzled that no one has invested in building a really good developer experience for it2. A couple of weeks ago, after ~250 hours of effort over three months3 on evenings, weekends, and vacation days, I finally released syntaqlite (GitHub), fulfilling…
Most SQL tools treat SQLite as a “flavor” of a generic SQL parser. They approximate the language, which means they break on SQLite-exclusive features like virtual tables, miss syntax like UPSERT, and ignore the 22 compile-time flags that change the syntax SQLite accepts. So I built syntaqlite: an open-source parser, formatter, validator, and LSP built directly on SQLite’s own Lemon-generated…
We’ve recently been looking into optimizing rendering performance of the Perfetto UI on large traces. We discovered that there was some inefficiency in our data fetching logic, especially when you’re very zoomed out. In this case, there can be a lot of slices (spans) which are so small that they take less than one pixel of width. So for each pixel, we need to figure out “what is the event which we…
Over the last few weeks, three new products have announced themselves on Hacker News to great success, each making the frontpage: Sprites (fly.io) with 508 votes and hit #7 exe.dev with 457 votes and hit #2 shellbox.dev with 316 votes and hit #4 All three have a very simple pitch: they will give you full access to Linux virtual machines to act as a sandboxed developer environment in the cloud. At…
When I was a junior engineer, my manager would occasionally confide his frustrations to me in our weekly 1:1s. He would point out a project another team was working on and say, “I don’t believe that project will go anywhere, they’re solving the wrong problem.” I used to wonder, “But you are very senior, why don’t you just go and speak to them about your concerns?” It felt like a waste of his…
Two people. Eighteen accounts spanning checking, savings, credit cards, investments. Three currencies. Twenty minutes of work every week. One net worth number I actually trust. The payoff: A single, trustworthy net worth number growing over time. No app did exactly what I needed, so I built my own personal finance system using plain-text accounting principles and a powerful Python library called…
Just a quick note documenting some recent changes to the blog. Nothing groundbreaking, but enough accumulated updates that I wanted to write them down. Homepage Redesign# The homepage used to be a chronological list of articles; your classic default blog format. I’ve redesigned it into more of a two-pane “dashboard” feel. The reason? My content is quite varied: I have long essays and technical…
Lately I’ve been reading Sean Goedecke’s essays on being a Staff+ engineer. His work (particularly Software engineering under the spotlight and It’s Not Your Codebase) is razor-sharp and feels painfully familiar to anyone in Big Tech. On paper, I fit the mold he describes: I’m a Senior Staff engineer at Google. Yet, reading his work left me with a lingering sense of unease. At first, I dismissed…
It’s Friday at 4pm. I’ve just closed my 12th bug of the week. My brain is completely fried. And I’m staring at the bug leaderboard, genuinely sad that Monday means going back to regular work. Which is weird because I love regular work. But fixit weeks have a special place in my heart. What’s a fixit, you ask?# Once a quarter or so, my org with ~45 software engineers stops all regular work for a…
If you do Linux systems programming, you will have likely pored over man pages, either on the command line or, my personal preference, using the excellent man7.org or linux.die.net. I’ve always seen the numbers in sleep(3) and read(2) and idly wondered what they meant, but never actually bothered to look them up. That is, until a review comment on a pull request: // Behaves like man 2 basename…
Last week, I came across Don’t Build an Audience. It’s a fascinating post and has been occupying a lot of my “free thinking” time. I strongly suggest reading it as it’s well written and excellently argued. To summarise what it tries to say: The market for written content on the web (blog posts, articles etc) is “efficient”: in other words, great work will find its audience without you needing to…
As an “SQLite consultant” for my local area of Google, I often have people come to me having written SQL like: SELECT CAST(bar AS STRING) AS baz FROM foo and ask me “Why is baz always an integer?! Have I hit an SQLite bug?”. I have to again reach for my list of “odd quirks that SQLite has that people don’t know about”. Because this is not a bug, at least according to the SQLite manual. Instead,…
A few weeks ago, I wrote about “The Documentation System” and how valuable I found it. As I dug deeper into researching how best to apply the principles outlined there, I came across Diátaxis. Written by the same author after they left Divio, Diátaxis is a distillation of all the principles with much more guidance in how to apply the framework (e.g. giving more examples), diving more into the…
I gave a talk at the 2025 Tracing Summit last month titled “Perfetto: The Swiss Army Knife of Linux Client/Embedded Tracing”. My goal in this talk was to show how Linux kernel, systems and embedded developers can use Perfetto when debugging and root-causing performance issues in their respective domains. Even though the Perfetto UI is primarily built for viewing Android or Chrome traces, it is a…
Sometimes you run into a truly inspirational piece of software that it’s a wonder even exists. I found 0x0.st recently and it very much falls into this bucket. It’s essentially a simple, no-account, temporary file hosting site where you can just upload a file using a simple HTTP POST and the site will host it for you for between 30 days and 1 year depending on the size of the file. Uploading a…
The Perfetto UI is a fascinating project to work on because it often faces performance problems which you wouldn’t see in more “normal” webapps. I learn about all sorts of weird web features by reviewing PRs for the UI. Two such features I just learned about: will-change (PR): a hint, to be used sparingly, to tell the browser that a certain property of a DOM element will change in the near future.…
The Perfetto team spent a lot of time earlier this year rewriting our documentation to be more useful for the average developer. We struggled a lot to figure out “what is the best way to structure our documentation”. When reading Examples are the best documentation today, I came across The Documentation System, an approach to structuring developer documentation. Reading through it, I couldn’t help…
I recently stumbled across this post on lobste.rs about a project called traceboot which allows visualizing the Linux boot process using lightweight ftrace events and Perfetto. The author had some commentary about their experience trying to order tracks in Perfetto: Ordering tracks with perfetto has been ridiculously complicated. It has taken the majority of the time of this project! Upstream’s…
I’ve been using Claude Code extensively for personal projects, and similar AI coding tools at work. Recently I came across this excellent blog post that resonated with a lot of my experience. One part stuck with me though: Noah emphasizes that tools fail with LLMs when they’re “overly complex,” with the Unix philosophy being particularly well-suited for tool calling. But then I thought about git.…
One of my biggest weaknesses as a software engineer is procrastination when facing a new project. When the scope is unclear, I have a tendency to wait until I feel I’ve “felt out” the problem to start doing anything. I know I’ll feel better and work much faster when I get “stuck in” but I still struggle with that first step, overcoming the “activation energy” required to engage with the details.…
TLDR: Explain how the V4L2 M2M API works through the use-case of implementing hardware video encoding on the Raspberry Pi. This knowledge is generally useful as V4L2 is the de-facto generic API for hardware decoding and encoding on Linux. Background My journey started at this video on the excellent Craft Computing YouTube channel which showed how to setup TinyPilot, a Python app for KVM over IP…