* [LARTC] using cpu cycle counter on smp
@ 2006-11-28 23:16 Marek Kierdelewicz
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From: Marek Kierdelewicz @ 2006-11-28 23:16 UTC (permalink / raw)
To: lartc
Hi there,
I was wondering if it's possible to use PSCHED_CPU (cpu cycle counter
as clock source for QoS). Normally kernel menuconfig forbids it due
to lack of synchronization of counters on different cpu, but:
http://uwsg.iu.edu/hypermail/linux/kernel/9902.0/0053.html
and quoting interesting part...
-------------
checking TSC synchronization across CPUs:
BIOS BUG: CPU#0 improperly initialized, has -25 usecs TSC skew! FIXED.
BIOS BUG: CPU#1 improperly initialized, has 25 usecs TSC skew! FIXED.
-------------
... we can see TSC is synchronized during boot process. So, is it or is
it not possible/prudent to use PSCHED_CPU on x86/x86_64, where TSCs
are used?
pozdrawiam,
Marek Kierdelewicz
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