trentnelson

6 ms·

1.
by trentnelson 13d ago
May need to be fail-closed.
2.
by trentnelson 1mo ago
Possibly an unpopular opinion on this forum, but virtual memory has always been one of the strengths of the NT kernel. (And integration between the cache manager, virtual memory manager, file system (NTFS), overlapped I/O, completion
3.
by trentnelson 3mo ago
Not ssh related but I regularly suspend my terminal with Ctrl-S by accident, usually when going for Ctrl-C/V. That was a nightmare to triage back in the late 90s when I did it. Thankfully Ctrl-Q (I think it’s Q) “resumes”, so, easy fi
4.
by trentnelson 6mo ago
WaitForMultipleObjects is fascinating behind the scenes. A single thread can wait on up to 64 independent events, which is done by plumbing the KTHREAD data structure with literally 64 slots for dispatcher header stuff, plus all the suppor
5.
by trentnelson 6mo ago
When the PDIMMs were used with an appropriate file system + kernel, it was pretty cool. NTFS + DAX + kernel support yielded a file system where mmap’ing didn’t page fault. No page faults because the file content is already there, instantl
6.
by trentnelson 6mo ago
Well now I’m curious how they did it in the 90s. Some poor schmo doing pixel by pixel font creation?
7.
by trentnelson 8mo ago
If you’ve got an existing paragraph written that you just know could be rephrased more eloquently, and can describe the type of rephrasing/restructuring you want… LLMs absolutely slap at that.
8.
by trentnelson 8mo ago
I mean to be fair, WSL1 and WSL2 are extremely successful engineering efforts by Microsoft. I can’t imagine having to go back to the Cygwin days.
9.
by trentnelson 11mo ago
I finished this article in February this year, just before joining NVIDIA. It didn't get officially published then for... reasons. Posting now despite some of the information being a little out of date as I still think the content mi
10.
PyTorch and Python Free-Threading(trent.me)
10 points by trentnelson 11mo ago|2 comments
11.
by trentnelson 1y ago
Oh man, the Abit motherboards! That takes me back. How much did this cost and at what time? Presume very late 90s.
12.
by trentnelson 2y ago
I remember my first job in 2000, straight out of 1.5 years of college, getting to play directly with Digital UNIX and Alpha processors! The Alpha 21264 was a beast at the time.
13.
by trentnelson 2y ago
Based on an earlier comment, I think the person you're replying to is the author of aider.
14.
by trentnelson 2y ago
It’s insane how hard hovering is. I had about 35 hours of fixed wing time, and treated myself to a helicopter lesson for my birthday. Hovering was so humbling! You’d be stable for a few seconds and then oops now we’re suddenly crabbing ba
15.
by trentnelson 2y ago
Had any exposure to r=2 hypergraph implementations on the GPU? Ideally with an efficient way to determine if the graph is acyclic? (The CPU algos for doing this work great on CPUs but are woeful on GPUs.)
16.
by trentnelson 2y ago
None of the UNIXes have the notion of WriteFile with an OVERLAPPED structure, that’s the key to NT’s asynchronous I/O. Nor do they have anything like IOCP, where the kernel is aware of the number of threads servicing a completion port,
17.
by trentnelson 2y ago
Yeah I’d definitely include RegisteredIO and IoRing. When I was interviewing at Microsoft a few years back, I was actually interviewed by the chap that wrote RegisteredIO! Thought that was neat.
18.
by trentnelson 2y ago
I should do an updated version of that deck with io_uring and sans the PyParallel element. I still think it’s a good resource for depicting the differences in I/O between NT & UNIX. And yeah, IOCP has implicit awareness of concurr
19.
by trentnelson 2y ago
FWIW, on Windows, the ETW event instrumentation that captures dispatch (i.e. thread scheduling) and loader info (I think it's literally the DISPATCH+LOADER flags to xperf) solves this problem, which, inherently is: at any arbitrary poi
20.
by trentnelson 2y ago
Interesting... I've been lamenting the absence of .pdbs on Linux. It sounds like this would allow dissasociating symbol info from the build artifact itself? (There's no other out-of-the-box solution to this right? i.e. having sy
21.
by trentnelson 2y ago
I like the idea of hacking the crap out of `compile_commands.json` and subverting it for your evil machinations outside of the normal build process. Such a hideously pragmatic tip.
22.
by trentnelson 2y ago
That's neat. The modern equivalent to that these days, on Windows, is to leverage ETW and Windows Performance Analyzer. Potentially with a custom plugin that can visualize your specific perf data as a first-class WPA citizen (i.e. in
23.
by trentnelson 2y ago
Had fun googling those system names. NX801: https://www.tpc.org/results/individual_results/axil/axil.nx8... 200 9.1GB SCSI disks for 1.8TB! And still only 4GB RAM on that SQL Server 6.5 box they used for TPC
24.
by trentnelson 2y ago
I should probably do an updated talk/article/deck on io_uring. I really do like NT internals though.
25.
by trentnelson 2y ago
What happens when you press page up or down in tmux? Have you configured it to scroll page up & down? Or do you do that via Ctrl-B ] or whatever the magic incantation was?
26.
by trentnelson 2y ago
Yeah I was thinking how different those days seemed. And how hard it would be to run into this sort of content these days if you’re a generally curious youngster.
27.
by trentnelson 2y ago
And train control systems.
28.
by trentnelson 2y ago
This has made stepping through C++ in gdb slightly less painful for me: use gdb's skip command. E.g., in my ~/.gdbinit: # C++ stdlib skip -gfi /home/trent/mambaforge/envs/td/x86_64-conda-li
29.
by trentnelson 3y ago
What’s its fastest index function look like in assembly? My MultiplyShiftRX clocks in at like 5 cycles on x64 and 3 cycles on my M1. Mine is optimized for offline table generation so construction speed isn’t really relevant for its primar
30.
by trentnelson 3y ago
Hey, if you're looking for a real-world pragmatic and performant implementation of a theoretically-cool algorithm, my https://github.com/tpn/perfecthash project might fit the bill. It's geared to generating p

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