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x86, vmware: Preset lpj values when on VMware.

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When running on VMware's platform, we have seen situations where
the AP's try to calibrate the lpj values and fail to get good calibration
runs becasue of timing issues. As a result delays don't work correctly
on all cpus.

The solutions is to set preset_lpj value based on the current tsc frequency
value. This is similar to what KVM does as well.

Signed-off-by: Alok N Kataria <akataria@vmware.com>
LKML-Reference: <1280790637.14933.29.camel@ank32.eng.vmware.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Alok Kataria 2010-08-02 16:10:37 -07:00 committed by H. Peter Anvin
parent 9fe6206f40
commit 9f242dc10e
1 changed files with 8 additions and 1 deletions
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9
arch/x86/kernel/cpu/vmware.c
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@ -51,7 +51,7 @@ static inline int __vmware_platform(void)
static unsigned long vmware_get_tsc_khz(void)
{
uint64_t tsc_hz;
uint64_t tsc_hz, lpj;
uint32_t eax, ebx, ecx, edx;
VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
@ -62,6 +62,13 @@ static unsigned long vmware_get_tsc_khz(void)
printk(KERN_INFO "TSC freq read from hypervisor : %lu.%03lu MHz\n",
(unsigned long) tsc_hz / 1000,
(unsigned long) tsc_hz % 1000);
if (!preset_lpj) {
lpj = ((u64)tsc_hz * 1000);
do_div(lpj, HZ);
preset_lpj = lpj;
}
return tsc_hz;
}