Paul Khuong / is on Nostr

Last Notes

2024-05-23 00:55:54

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@npub1c9m…9xjd I feel like that would be the same as squaring the circle?

2024-03-01 22:57:50

"a conceptually simple and computationally cheap extrapolation scheme strictly improves the worst-case convergence rate. […] improves the best possible worst-case performance by the same amount as conducting O(sqrt(N/log(N)) more gradient steps."
https://optimization-online.org/2024/02/on-averaging-and-extrapolation-for-gradient-descent/

2023-12-06 19:16:39

Love to see awk complain about missing mpfr symbols in the middle of a vivado log file.

2023-11-03 00:23:53

RIP itanium… I remember when it was an even more annoying target than Alpha, yet worth the effort.

2023-10-23 13:13:22

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@npub1y0e…mm9n 50% of physical RAM is just the default size limit on Linux. You can make a tmpfs mount as large or small as you want.

2023-10-23 11:20:31

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@npub1y0e…mm9n Linux flushes dirty pages on a timer or when they exceed a fraction of free memory. ~10 years ago I saw spikes of badly scheduled flushing I/O with LMDB/XFS, for data that fit in RAM. You can try to tune around that's behaviour, but the failure modes when reality doesn't match the tuned values tend to be even worse (e.g., multi-minute lockups).

2023-10-21 14:21:11

Programmers: the stack is the most efficient place to stuff temporary values.
Also programmers: this executable's filename is load-bearing for performance.
(https://people.cs.umass.edu/~emery/pubs/stabilizer-asplos13.pdf)

2023-09-16 02:45:26

I don't know if all the async folks realise how much of a latency hit we take with event systems like epoll, compared to just blocking (or completions/io_uring), especially when there's a lot of load.
Whenever the kernel handles external inputs, it now acquires a hot locks to wake waiters up… when the waiter finally gets a timeslice, it immediately goes back in the kernel to actually perform the operation it didn't do want to block on :/ And that's without traps like thundering herds, edge triggering, or epoll's LIFO policy.