Re: [discuss] Re: [PATCH] Allow all Opteron processors to changepstateat same time
From: Bhavana Nagendra
Date: Thu Jul 13 2006 - 10:59:19 EST
Here are some results without changing frequencies on a system whose
BIOS does not support Power Now! on MP systems:
Basically the system booted up with "nohpet, nopmtimer"i.e. using TSC as
the GTOD time source and system stayed idle for 13 hours. There
appears to be drift of 20 secs in the CPU 2 readings. This TSC drift
could worsen when
the system is active and doing GTOD operations and/or when system is up
a lot longer.
CPU 2: Syncing TSC to CPU 0.
CPU 2: synchronized TSC with CPU 0 (last diff -108 cycles, maxerr 826
cycles)
CPU 3: Syncing TSC to CPU 0.
CPU 3: synchronized TSC with CPU 0 (last diff -119 cycles, maxerr 845
cycles)
*** CPUs go offline ***
*** back online ***
CPU 2: Syncing TSC to CPU 0.
CPU 2: synchronized TSC with CPU 0 (last diff -117 cycles, maxerr 846
cycles)
CPU 3: Syncing TSC to CPU 0.
CPU 3: synchronized TSC with CPU 0 (last diff -117 cycles, maxerr 845
cycles)
shin, jacob wrote:
On Thursday, July 13, 2006 9:32 AM Deguara, Joachim wrote:
parallel sounds fun, but I don't get it. Two machine or trying to go
online and offline at the same time? Firestorming two busy parallel
while loops, one turning the core offline and the other online, did
not bring an oops so I guess this kernel is in the clear in that
regard.
I can't get it to crash again and I am afraid that it crashed under an
old devel kernel. After another ~20 hour test with heavy freq changes
with the tscsync patch
There were several different issues w/ powernow + cpu hotplug in the
past. Good to hear that the latest kernel doesn't oops.. I believe
cpu hotplug is needed for suspend to work..
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