Messages in this thread | | | Subject | Re: [PATCH] Configure IDE probe delays | From | Alan Cox <> | Date | Wed, 01 Sep 2004 19:42:09 +0100 |
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On Mer, 2004-09-01 at 20:36, Lee Revell wrote: > The effect can be measured using a recent version of the voluntary > preemption patches, and disabling hardirq preemption. In this situation > the IDE I/O completion is by far the longest non-preemptible code path, > so can be easily profiled from the latency traces.
A lot of IDE controllers hold off the CPU for long times when you do I/O cycles. The other factor is PIO which defaults to IRQ masking for safety on old controllers. For PCI we should probably default the other way.
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