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ed5316d445
Ensure that no SMI interrupts occur between the read of the HPET & TSC in the clock calibration loop. I noticed that a 2.66GHz system incorrectly detected the processor clock speed about 1/7 of the time: time.c: Detected 2660.005 MHz processor. (most of the time) time.c: Detected 2988.203 MHz processor. (sometime) The problem is caused by an SMI interrupt occuring in hpet_calibrate_tsc() between the read of the HPET & TSC. Prior to switching the BIOS into ACPI mode, it appears that every 27msec an SMI interrupt occurs. The SMI interrupt takes 4.8 msec to process. Note: On my test system, TICK_MIN had to be >380. I picked 5000 to minimize risk of having a value that is too small for other platforms. Signed-off-by: Jack Steiner <steiner@sgi.com> Signed-off-by: Andi Kleen <ak@suse.de> arch/x86_64/kernel/time.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) |
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