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| author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2015-08-19 09:54:24 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-08-21 08:44:38 +0200 |
| commit | 88c9281a9fba67636ab26c1fd6afbc78a632374f (patch) | |
| tree | 3533bbf23d002ee4cb2c95f3b2beca42f4e90a16 /arch | |
| parent | 955381dd65654bd6f066408823691db8fa7d05bb (diff) | |
| download | linux-88c9281a9fba67636ab26c1fd6afbc78a632374f.tar.gz linux-88c9281a9fba67636ab26c1fd6afbc78a632374f.tar.bz2 linux-88c9281a9fba67636ab26c1fd6afbc78a632374f.zip | |
x86/hyperv: Mark the Hyper-V TSC as unstable
The Hyper-V top-level functional specification states, that
"algorithms should be resilient to sudden jumps forward or
backward in the TSC value", this means that we should consider
TSC as unstable. In some cases tsc tests are able to detect the
instability, it was detected in 543 out of 646 boots in my
testing:
Measured 6277 cycles TSC warp between CPUs, turning off TSC clock.
tsc: Marking TSC unstable due to check_tsc_sync_source failed
This is, however, just a heuristic. On Hyper-V platform there
are two good clocksources: MSR-based hyperv_clocksource and
recently introduced TSC page.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: devel@linuxdriverproject.org
Link: http://lkml.kernel.org/r/1440003264-9949-1-git-send-email-vkuznets@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/cpu/mshyperv.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index aad4bd84b475..6fd023d7492d 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -141,6 +141,7 @@ static void __init ms_hyperv_init_platform(void) no_timer_check = 1; #endif + mark_tsc_unstable("running on Hyper-V"); } const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = { |