Messages in this thread | | | Subject | Re: 2.6.19-rc1: x86_64 slowdown in lmbench's fork | From | Tim Chen <> | Date | Fri, 03 Nov 2006 12:25:17 -0800 |
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On Fri, 2006-11-03 at 18:47 +0100, Andi Kleen wrote: > > So unless there is some other array that is sized by NR_IRQs > > in the context switch path which could account for this in > > other ways. It looks like you just got unlucky. > > > TLB/cache profiling data might be useful? > My bet would be more on cache effects. >
The TLB miss, cache miss and page walk profiles did not change when I measured it.
I have a suspicion that the overhead to pin parent and child processes to specific cpu had something to do with the change in time observed. Lmbench includes this overhead in the fork time it reported. I had chosen the lmbench option to set parent and child process on specific cpu.
When I skip this by picking another lmbench option to let scheduler pick the placement of parent and child process. I see that the fork time now stays unchanged with this setting. Wonder if the increase in time is in sched_setaffinity.
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