diff options
| author | Venki Pallipadi <venkatesh.pallipadi@intel.com> | 2008-11-17 17:43:58 -0500 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-11-17 18:15:02 -0500 |
| commit | 93ce99e849433ede4ce8b410b749dc0cad1100b2 (patch) | |
| tree | 0481209f97a05a3851f536b2e16bd2868f83d842 /arch/x86/kernel/pcspeaker.c | |
| parent | 26a3e99160cfb06a0a33e25b9fb0d516e2cc680d (diff) | |
x86: add rdtsc barrier to TSC sync check
Impact: fix incorrectly marked unstable TSC clock
Patch (commit 0d12cdd "sched: improve sched_clock() performance") has
a regression on one of the test systems here.
With the patch, I see:
checking TSC synchronization [CPU#0 -> CPU#1]:
Measured 28 cycles TSC warp between CPUs, turning off TSC clock.
Marking TSC unstable due to check_tsc_sync_source failed
Whereas, without the patch syncs pass fine on all CPUs:
checking TSC synchronization [CPU#0 -> CPU#1]: passed.
Due to this, TSC is marked unstable, when it is not actually unstable.
This is because syncs in check_tsc_wrap() goes away due to this commit.
As per the discussion on this thread, correct way to fix this is to add
explicit syncs as below?
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/pcspeaker.c')
0 files changed, 0 insertions, 0 deletions