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    SubjectRe: [Openipmi-developer] Improving IPMI performance under load
    Martin Wilck wrote:
    > Hi Corey,
    >
    > yesterday I posted some results about the IPMI performance under CPU
    > load, which can be up to 25 times slower than in an idle system. I think
    > it might be worthwhile to try to improve that behavior as well.
    >
    Yes, that would be expected, as kipmid would never be scheduled in a
    busy system, and it would just be the timer driving things.

    > I made a variation of my patch which introduces a second parameter
    > (kipmid_min_busy) that causes kipmid not to call schedule() for a
    > certain amount of time. Thus if there's IPMI traffic pending, kipmid
    > will busy-loop for kipmid_min_busy seconds, then starting to schedule()
    > in each loop as it does now, and finally go to sleep when
    > kipmid_max_busy is reached. At the same time, I changed the nice value
    > of kipmid from 19 to 0.
    >
    I would guess that changing the nice value is the main thing that caused
    the difference. The other changes probably didn't make as big a difference.

    > With this patch and e.g. min_busy=100 and max_busy=200, there is no
    > noticeable difference any more between IPMI performance with and without
    > CPU load.
    >
    > The patch + results still need cleanup, therefore I am not sending it
    > right now. Just wanted to hear what you think.
    >
    I'm ok with tuning like this, but most users are probably not going to
    want this type of behavior.

    -corey


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