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Improve Windows sleep accuracy from 15ms to 15µs

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Justine Tunney 2024-12-06 23:00:07 -08:00
parent b40140e6c5
commit b490e23d63
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GPG key ID: BE714B4575D6E328
16 changed files with 189 additions and 67 deletions
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7
libc/calls/pause-nt.c
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@ -18,21 +18,20 @@
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/internal.h"
#include "libc/calls/struct/sigset.internal.h"
#include "libc/calls/struct/timespec.h"
#include "libc/calls/syscall_support-nt.internal.h"
#ifdef __x86_64__
textwindows int sys_pause_nt(void) {
int rc;
// we don't strictly need to block signals, but it reduces signal
// delivery latency, by preventing other threads from delivering a
// signal asynchronously. it takes about ~5us to deliver a signal
// using SetEvent() whereas it takes ~30us to use SuspendThread(),
// GetThreadContext(), SetThreadContext(), and ResumeThread().
BLOCK_SIGNALS;
while (!(rc = _park_norestart(-1u, 0)))
donothing;
_park_norestart(timespec_max, 0);
ALLOW_SIGNALS;
return rc;
return -1;
}
#endif /* __x86_64__ */