Messages in this thread | | | Date | Wed, 9 Mar 2005 14:44:58 -0800 | From | Andrew Morton <> | Subject | Re: Direct io on block device has performance regression on 2.6.x kernel |
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"Chen, Kenneth W" <kenneth.w.chen@intel.com> wrote: > > > Did you generate a kernel profile? > > Top 40 kernel hot functions, percentage is normalized to kernel utilization. > > _spin_unlock_irqrestore 23.54% > _spin_unlock_irq 19.27%
Cripes.
Is that with CONFIG_PREEMPT? If so, and if you disable CONFIG_PREEMPT, this cost should be accounting the the spin_unlock() caller and we can see who the culprit is. Perhaps dio->bio_lock.
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