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/openbmc/linux/arch/x86/kernel/cpu/ |
H A D | intel.c | 6c56ccec Thu Dec 17 14:27:02 CST 2009 Pallipadi, Venkatesh <venkatesh.pallipadi@intel.com> x86: Reenable TSC sync check at boot, even with NONSTOP_TSC
Commit 83ce4009 did the following change If the TSC is constant and non-stop, also set it reliable.
But, there seems to be few systems that will end up with TSC warp across sockets, depending on how the cpus come out of reset. Skipping TSC sync test on such systems may result in time inconsistency later.
So, reenable TSC sync test even on constant and non-stop TSC systems. Set, sched_clock_stable to 1 by default and reset it in mark_tsc_unstable, if TSC sync fails.
This change still gives perf benefit mentioned in 83ce4009 for systems where TSC is reliable.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Acked-by: Suresh Siddha <suresh.b.siddha@intel.com> LKML-Reference: <20091217202702.GA18015@linux-os.sc.intel.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com> 6c56ccec Thu Dec 17 14:27:02 CST 2009 Pallipadi, Venkatesh <venkatesh.pallipadi@intel.com> x86: Reenable TSC sync check at boot, even with NONSTOP_TSC Commit 83ce4009 did the following change If the TSC is constant and non-stop, also set it reliable. But, there seems to be few systems that will end up with TSC warp across sockets, depending on how the cpus come out of reset. Skipping TSC sync test on such systems may result in time inconsistency later. So, reenable TSC sync test even on constant and non-stop TSC systems. Set, sched_clock_stable to 1 by default and reset it in mark_tsc_unstable, if TSC sync fails. This change still gives perf benefit mentioned in 83ce4009 for systems where TSC is reliable. Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Acked-by: Suresh Siddha <suresh.b.siddha@intel.com> LKML-Reference: <20091217202702.GA18015@linux-os.sc.intel.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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/openbmc/linux/arch/x86/kernel/ |
H A D | tsc.c | 6c56ccec Thu Dec 17 14:27:02 CST 2009 Pallipadi, Venkatesh <venkatesh.pallipadi@intel.com> x86: Reenable TSC sync check at boot, even with NONSTOP_TSC
Commit 83ce4009 did the following change If the TSC is constant and non-stop, also set it reliable.
But, there seems to be few systems that will end up with TSC warp across sockets, depending on how the cpus come out of reset. Skipping TSC sync test on such systems may result in time inconsistency later.
So, reenable TSC sync test even on constant and non-stop TSC systems. Set, sched_clock_stable to 1 by default and reset it in mark_tsc_unstable, if TSC sync fails.
This change still gives perf benefit mentioned in 83ce4009 for systems where TSC is reliable.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Acked-by: Suresh Siddha <suresh.b.siddha@intel.com> LKML-Reference: <20091217202702.GA18015@linux-os.sc.intel.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com> 6c56ccec Thu Dec 17 14:27:02 CST 2009 Pallipadi, Venkatesh <venkatesh.pallipadi@intel.com> x86: Reenable TSC sync check at boot, even with NONSTOP_TSC Commit 83ce4009 did the following change If the TSC is constant and non-stop, also set it reliable. But, there seems to be few systems that will end up with TSC warp across sockets, depending on how the cpus come out of reset. Skipping TSC sync test on such systems may result in time inconsistency later. So, reenable TSC sync test even on constant and non-stop TSC systems. Set, sched_clock_stable to 1 by default and reset it in mark_tsc_unstable, if TSC sync fails. This change still gives perf benefit mentioned in 83ce4009 for systems where TSC is reliable. Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Acked-by: Suresh Siddha <suresh.b.siddha@intel.com> LKML-Reference: <20091217202702.GA18015@linux-os.sc.intel.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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