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

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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>
This commit is contained in:
Andi Kleen 2006-09-26 10:52:41 +02:00 committed by Andi Kleen
parent 9ddab42d1e
commit 2049336f60
1 changed files with 6 additions and 0 deletions
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6
arch/x86_64/kernel/setup.c
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@ -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)