Date: Wed, 30 Jun 2021 05:08:12 GMT From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: f027b4f41fb1 - stable/13 - vdso: lower precision of vdso implementation of CLOCK_MONOTONIC_FAST and CLOCK_UPTIME_FAST Message-ID: <202106300508.15U58CDJ097081@gitrepo.freebsd.org>
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The branch stable/13 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=f027b4f41fb1b748070928175cdf2f57baf66c3a commit f027b4f41fb1b748070928175cdf2f57baf66c3a Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2021-06-22 23:24:08 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2021-06-30 04:42:06 +0000 vdso: lower precision of vdso implementation of CLOCK_MONOTONIC_FAST and CLOCK_UPTIME_FAST (cherry picked from commit 60b0ad10dd0fc7ff6892ecc7ba3458482fcc064c) --- lib/libc/sys/__vdso_gettimeofday.c | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) diff --git a/lib/libc/sys/__vdso_gettimeofday.c b/lib/libc/sys/__vdso_gettimeofday.c index 4c1f4bda23e1..c1457a54d37e 100644 --- a/lib/libc/sys/__vdso_gettimeofday.c +++ b/lib/libc/sys/__vdso_gettimeofday.c @@ -106,6 +106,30 @@ binuptime(struct bintime *bt, struct vdso_timekeep *tk, bool abs) return (0); } +static int +getnanouptime(struct bintime *bt, struct vdso_timekeep *tk) +{ + struct vdso_timehands *th; + uint32_t curr, gen; + + do { + if (!tk->tk_enabled) + return (ENOSYS); + + curr = atomic_load_acq_32(&tk->tk_current); + th = &tk->tk_th[curr]; + gen = atomic_load_acq_32(&th->th_gen); + *bt = th->th_offset; + + /* + * Ensure that the load of th_offset is completed + * before the load of th_gen. + */ + atomic_thread_fence_acq(); + } while (curr != tk->tk_current || gen == 0 || gen != th->th_gen); + return (0); +} + static struct vdso_timekeep *tk; #pragma weak __vdso_gettimeofday @@ -154,9 +178,11 @@ __vdso_clock_gettime(clockid_t clock_id, struct timespec *ts) break; case CLOCK_MONOTONIC: case CLOCK_MONOTONIC_PRECISE: - case CLOCK_MONOTONIC_FAST: case CLOCK_UPTIME: case CLOCK_UPTIME_PRECISE: + error = binuptime(&bt, tk, false); + break; + case CLOCK_MONOTONIC_FAST: case CLOCK_UPTIME_FAST: error = getnanouptime(&bt, tk); break;
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