Messages in this thread |  | | From | (Linus Torvalds) | Subject | Re: broken VM in 2.4.10-pre9 | Date | Sun, 16 Sep 2001 19:37:31 +0000 (UTC) |
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In article <1000722338.14005.0.camel@x153.internalnet>, Tonu Samuel <tonu@please.do.not.remove.this.spam.ee> wrote: > >Problem still exists and persists. Not long time ago man from Yahoo >described well case when change from 2.2.19 to 2.4.x caused performance >problems. On 2.2.19 everything ran fine. They have MySQL running+did >backups from disk. After upgrade to 2.4.x MySQL performance felt down on >backup time. They investigated stuff and found that MySQL daemon gets >swapped out in the middle of usage to make room for buffers.
Note that if you're using a raw device backup strategy (ie "e2dump" or similar), that is expected: 2.4.x up until about 2.4.7 gave _much_ too much preference to the buffer cache.
That should actually have been fixed in 2.4.8. We used to mark buffer pages much too active.
> In summary: >this made both sql and backup double slow. Even increasing memory from >1G->2G didn't helped. Finally they disabled swap at all and problem >lost.
You just hid the problem - by disabling swap the buffer cache couldn't grow without bounds any more, and the proper buffer cache shrinking couldn't happen.
Try 2.4.8 or later.
>If you do not want to change it back as it was in 2.2.x then would be >good if this is tunable somehow.
Tuning for bugs?
What do you want to happen? You want to have an interface like
echo 0 > /proc/bugs/mm
that makes mm bugs go away?
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