RE: Direct io on block device has performance regression on 2.6.x kernel

From: Chen, Kenneth W
Date: Wed Mar 09 2005 - 20:34:44 EST

Jesse Barnes wrote on Wednesday, March 09, 2005 3:53 PM
> > "Chen, Kenneth W" <kenneth.w.chen@xxxxxxxxx> writes:
> > > Just to clarify here, these data need to be taken at grain of salt. A
> > > high count in _spin_unlock_* functions do not automatically points to
> > > lock contention. It's one of the blind spot syndrome with timer based
> > > profile on ia64. There are some lock contentions in 2.6 kernel that
> > > we are staring at. Please do not misinterpret the number here.
> >
> > Why don't you use oprofileÂ>? It uses NMIs and can profile "inside"
> > interrupt disabled sections.
> Oh, and there are other ways of doing interrupt off profiling by using the
> PMU. q-tools can do this I think.

Thank you all for the suggestions. I'm well aware of q-tools and been using
it on and off. It's just that I don't have any data collected with q-tool
for that particular hardware/software benchmark configuration. I posted
with whatever data I have.

- Ken

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