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| author | jkim <jkim@FreeBSD.org> | 2011-04-12 22:41:52 +0000 |
|---|---|---|
| committer | jkim <jkim@FreeBSD.org> | 2011-04-12 22:41:52 +0000 |
| commit | 2092a06579f29873b4c1f7e4a294dfc71e455844 (patch) | |
| tree | 7c0abe482531b7bbd01df56d85c05ecfdb716aa8 /sys/x86/isa | |
| parent | 69382ad6929a850565f339c2aab52e63d50def3c (diff) | |
| download | FreeBSD-src-2092a06579f29873b4c1f7e4a294dfc71e455844.zip FreeBSD-src-2092a06579f29873b4c1f7e4a294dfc71e455844.tar.gz | |
Do not use TSC for DELAY(9) if it not P-state invariant to avoid possible
foot-shooting. DELAY() becomes unreliable when TSC frequency varies wildly,
especially cpufreq(4) and powerd(8) are used at the same time.
Diffstat (limited to 'sys/x86/isa')
| -rw-r--r-- | sys/x86/isa/clock.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/sys/x86/isa/clock.c b/sys/x86/isa/clock.c index d82dad7..5556ee6 100644 --- a/sys/x86/isa/clock.c +++ b/sys/x86/isa/clock.c @@ -263,7 +263,7 @@ delay_tc(int n) tc = timecounter; freq = atomic_load_acq_64(&tsc_freq); - if (freq != 0) { + if (tsc_is_invariant && freq != 0) { func = get_tsc; mask = ~0u; } else { |
