what is the better method to do tsc synchronized check?
From: Luming Yu
Date: Wed Mar 16 2011 - 22:56:44 EST
Hi there,
I tested two different methods to do TSC sync check on a Sandy Bridge system.
The first TSC sync check method is from upstream -38-rc that considers
TSC is synced.
The second TSC sync check method is from a 2.6.18 based kernel that
considers TSC
is NOT synced on the Sandy Bridge system. (I modified sync_tsc() to
just test (not modify TSC) on
the cpu being tested.)
[root@intel-sugarbay-DO-01 kernel]# dmesg | grep -i synchroniz
CPU 1: synchronized TSC with CPU 0 (last diff 29 cycles, maxerr 276 cycles)
CPU 2: synchronized TSC with CPU 0 (last diff 32 cycles, maxerr 280 cycles)
CPU 3: synchronized TSC with CPU 0 (last diff 31 cycles, maxerr 284 cycles)
Do you guy think we need to take 2.6.18-based tsc sync testing method
rather than the current one in upstream?
Any inputs are appreciated.
Thanks
Luming
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