Re: softirq considered harmful

From: David Miller
Date: Sat Aug 12 2006 - 21:07:02 EST

From: Andrew Morton <akpm@xxxxxxxx>
Date: Sat, 12 Aug 2006 17:45:49 -0700

> Is that also adding 150 usecs to each IO operation?

I have no idea, Jens hasn't done enough to narrow down the true cause
of the latencies he is seeing. So pinpointing it on anything specific
is highly premature at this stage.

My point was merely to encourage you to find out the facts before
tossing accusations around. :-) I/O completions via softirqs aren't
some new thing, in general, as the SCSI example shows, and GIT didn't
even exist when the scsi command completion via softirq changes went

Heck I think even Eric Youngdale was still an active developer of our
SCSI stack back then, that's a long time ago! :-)
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