Messages in this thread | | | Date | Mon, 19 Jul 2004 12:48:37 +0200 | From | Ingo Molnar <> | Subject | Re: [linux-audio-dev] Re: [announce] [patch] Voluntary Kernel Preemption Patch |
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* Lee Revell <rlrevell@joe-job.com> wrote:
> Just as a reference point, what do you think is the longest delay I > *should* be seeing? I recall hearing that BEOS guaranteed that > interrupts are never disabled for more than 50 usecs. This seems > achievable, as the average delay I am seeing is 15 usecs.
ATA hardirq latency can be as high as 700 usecs under load even on modern hw, when big DMA requests are created with long scatter-gather lists. We also moved some of the page IO completion code into irq context which further increased hardirq latencies. Since these all touch cold cachelines it all adds up quite quickly.
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