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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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36
libc/calls/clock_nanosleep-nt.c
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@ -16,6 +16,7 @@
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/atomic.h"
#include "libc/calls/internal.h"
#include "libc/calls/struct/sigset.internal.h"
#include "libc/calls/struct/timespec.h"
@ -23,26 +24,37 @@
#include "libc/calls/syscall-sysv.internal.h"
#include "libc/errno.h"
#include "libc/intrin/atomic.h"
#include "libc/nt/enum/status.h"
#include "libc/nt/ntdll.h"
#include "libc/stdio/sysparam.h"
#include "libc/sysv/consts/clock.h"
#include "libc/sysv/consts/timer.h"
#include "libc/thread/tls.h"
#ifdef __x86_64__
static atomic_int usingRes;
static atomic_bool changedRes;
static textwindows int sys_clock_nanosleep_nt_impl(int clock,
struct timespec abs,
sigset_t waitmask) {
uint32_t msdelay;
struct timespec now;
for (;;) {
if (sys_clock_gettime_nt(clock, &now))
return -1;
if (timespec_cmp(now, abs) >= 0)
return 0;
msdelay = timespec_tomillis(timespec_sub(abs, now));
msdelay = MIN(msdelay, -1u);
if (_park_norestart(msdelay, waitmask) == -1)
return -1;
}
struct timespec now, wall;
uint32_t minRes, maxRes, oldRes;
sys_clock_gettime_nt(0, &wall);
if (sys_clock_gettime_nt(clock, &now))
return -1;
bool wantRes = clock == CLOCK_REALTIME || //
clock == CLOCK_MONOTONIC || //
clock == CLOCK_BOOTTIME;
if (wantRes && !atomic_fetch_add(&usingRes, 1))
changedRes = NtSuccess(NtQueryTimerResolution(&minRes, &maxRes, &oldRes)) &&
NtSuccess(NtSetTimerResolution(maxRes, true, &oldRes));
if (timespec_cmp(abs, now) > 0)
wall = timespec_add(wall, timespec_sub(abs, now));
int rc = _park_norestart(wall, waitmask);
if (wantRes && atomic_fetch_sub(&usingRes, 1) == 1 && changedRes)
NtSetTimerResolution(0, false, &minRes);
return rc;
}
textwindows int sys_clock_nanosleep_nt(int clock, int flags,