Commits
Vitaly Kuznetsov committed 88c9281a9fb
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>