Messages in this thread Patch in this message | | | Date | Tue, 4 Nov 2008 10:27:20 -0500 | From | Prarit Bhargava <> | Subject | [PATCH] Warn of incorrect cpu_khz on AMD systems |
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If none of the perfctrs are free when calculating cpu_khz we default to using ctr 3 (ie, we just choose 3). This may lead to an incorrect tsc freq value which can cause the system to be unstable.
To aid in future debugging, WARN the user of a potential problem.
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
diff --git a/arch/x86/kernel/time_64.c b/arch/x86/kernel/time_64.c index cb19d65..86d71b3 100644 --- a/arch/x86/kernel/time_64.c +++ b/arch/x86/kernel/time_64.c @@ -80,6 +80,8 @@ unsigned long __init calibrate_cpu(void) break; no_ctr_free = (i == 4); if (no_ctr_free) { + printk(KERN_WARN "Warning: AMD perfctrs busy ... " + "cpu_khz value may be incorrect.\n"); i = 3; rdmsrl(MSR_K7_EVNTSEL3, evntsel3); wrmsrl(MSR_K7_EVNTSEL3, 0);
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