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x86/tsc: Skip TSC test and error messages if already unstable 

If the TSC has already been determined to be unstable, then checking
TSC ADJUST values is a waste of time and generates unnecessary error
messages.

Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dimitri Sivanich <dimitri.sivanich@hpe.com>
Reviewed-by: Russ Anderson <russ.anderson@hpe.com>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Bin Gao <bin.gao@linux.intel.com>
Link: https://lkml.kernel.org/r/20171012163202.060777495@stormcage.americas.sgi.com
This commit is contained in:
mike.travis@hpe.com 2017-10-12 11:32:03 -05:00 committed by Thomas Gleixner
parent 341102c3ef
commit 9514ececa5
1 changed files with 8 additions and 0 deletions
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8
arch/x86/kernel/tsc_sync.c
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@ -52,6 +52,10 @@ void tsc_verify_tsc_adjust(bool resume)
if (!boot_cpu_has(X86_FEATURE_TSC_ADJUST))
return;
/* Skip unnecessary error messages if TSC already unstable */
if (check_tsc_unstable())
return;
/* Rate limit the MSR check */
if (!resume && time_before(jiffies, adj->nextcheck))
return;
@ -114,6 +118,10 @@ bool __init tsc_store_and_check_tsc_adjust(bool bootcpu)
if (!boot_cpu_has(X86_FEATURE_TSC_ADJUST))
return false;
/* Skip unnecessary error messages if TSC already unstable */
if (check_tsc_unstable())
return false;
rdmsrl(MSR_IA32_TSC_ADJUST, bootval);
cur->bootval = bootval;
cur->nextcheck = jiffies + HZ;