Re: Direct io on block device has performance regression on 2.6.xkernel

From: Andi Kleen
Date: Wed Mar 09 2005 - 18:31:36 EST

"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.

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