Date: Sun, 16 Jan 2022 05:34:20 GMT From: Colin Percival <cperciva@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 7299cefe3949 - stable/13 - Skip TSC calibration if exact value known Message-ID: <202201160534.20G5YKtN028144@gitrepo.freebsd.org>
next in thread | raw e-mail | index | archive | help
The branch stable/13 has been updated by cperciva: URL: https://cgit.FreeBSD.org/src/commit/?id=7299cefe39493490b378ead0118ed2dbe3d36ebb commit 7299cefe39493490b378ead0118ed2dbe3d36ebb Author: Colin Percival <cperciva@FreeBSD.org> AuthorDate: 2021-12-30 19:43:15 +0000 Commit: Colin Percival <cperciva@FreeBSD.org> CommitDate: 2022-01-16 05:33:33 +0000 Skip TSC calibration if exact value known It's possible that the "early" TSC calibration gave us a value which is known to be exact; in that case, skip the later re-calibration. Differential Revision: https://reviews.freebsd.org/D33695 (cherry picked from commit 9cb3288287ba1b3c1d0ec891c552fc4b9472027e) --- sys/x86/x86/tsc.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/sys/x86/x86/tsc.c b/sys/x86/x86/tsc.c index b752ad18f058..7c4375979b3d 100644 --- a/sys/x86/x86/tsc.c +++ b/sys/x86/x86/tsc.c @@ -59,6 +59,7 @@ __FBSDID("$FreeBSD$"); uint64_t tsc_freq; int tsc_is_invariant; int tsc_perf_stat; +static int tsc_early_calib_exact; static eventhandler_tag tsc_levels_tag, tsc_pre_tag, tsc_post_tag; @@ -133,6 +134,7 @@ tsc_freq_vmware(void) tsc_freq = regs[0] | ((uint64_t)regs[1] << 32); } tsc_is_invariant = 1; + tsc_early_calib_exact = 1; } /* @@ -707,6 +709,8 @@ tsc_calibrate(void) if (tsc_disabled) return; + if (tsc_early_calib_exact) + goto calibrated; /* * Avoid using a low-quality timecounter to re-calibrate. In
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?202201160534.20G5YKtN028144>