Commit 9514ecec authored Oct 12, 2017 by mike.travis@hpe.com Committed by Thomas Gleixner Oct 16, 2017

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

parent 341102c3

arch/x86/kernel/tsc_sync.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -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;

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