Messages in this thread |  | | From | (Linus Torvalds) | Subject | Re: Terrible elevator performance in kernel 2.4.0-test8 | Date | 15 Sep 2000 13:29:25 -0700 |
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In article <Pine.LNX.4.21.0009141152480.1413-200000@elte.hu>, Ingo Molnar <mingo@elte.hu> wrote: > >i'm seeing similar problems. I think these problems started when the >elevator was rewritten, i believe it broke the proper unplugging of IO >devices. Does your performance problem get fixed by the attached >workaround?
If this helps, that implies that somebody is doing a (critical) IO request, without ever actually asking for the request to be _started_.
That sounds like a bug, and the patch looks like band-aid.
Where do we end up scheduling without starting the disk IO?
I'd rather add the disk schedule to _that_ place, instead of adding it to every re-schedule event.
(For example, on a multi-CPU system it should _not_ be the case that one CPU scheduling frequently should cause IO performance to go down - yet your patch will do exactly that).
Could you make it print out a backtrace instead when this happens (make it do it for the first few times, so as not to flood your console forever if it ends up being common..)
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