Re: High lock spin time for zone->lru_lock under extreme conditions
From: Nick Piggin
Date: Sat Jan 13 2007 - 02:55:54 EST
Ravikiran G Thirumalai wrote:
On Sat, Jan 13, 2007 at 03:39:45PM +1100, Nick Piggin wrote:
What is the "CS time"?
Critical Section :). This is the maximal time interval I measured from
t2 above to the time point we release the spin lock. This is the hold
time I guess.
It would be interesting to know how long the maximal lru_lock *hold* time
is,
which could give us a better indication of whether it is a hardware problem.
For example, if the maximum hold time is 10ms, that it might indicate a
hardware fairness problem.
The maximal hold time was about 3s.
Well then it doesn't seem very surprising that this could cause a 30s wait
time for one CPU in a 16 core system, regardless of fairness.
I guess most of the contention, and the lock hold times are coming from
vmscan? Do you know exactly which critical sections are the culprits?
--
SUSE Labs, Novell Inc.
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