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Commit 2049336f authored Sep 26, 2006 by Andi Kleen Committed by Andi Kleen Sep 26, 2006

[PATCH] Don't synchronize time reading on single core AMD systems



We do some additional CPU synchronization in gettimeofday et.al. to make
sure the time stamps are always monotonic over multiple CPUs. But on
single core systems that is not needed. So don't do it.

Signed-off-by: Andi Kleen <ak@suse.de>

parent 9ddab42d

arch/x86_64/kernel/setup.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -728,6 +728,12 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c)

		/* Fix cpuid4 emulation for more */
		num_cache_leaves = 3;

		/* When there is only one core no need to synchronize RDTSC */
		if (num_possible_cpus() == 1)
		set_bit(X86_FEATURE_SYNC_RDTSC, &c->x86_capability);
		else
		clear_bit(X86_FEATURE_SYNC_RDTSC, &c->x86_capability);
		}

		static void __cpuinit detect_ht(struct cpuinfo_x86 *c)