2.2.19pre3 and poor reponse to RT-scheduled processes?

From: Rafal Boni (rafal.boni@eDial.com)
Date: Fri Dec 29 2000 - 15:45:23 EST


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[...Please CC me on any replies, as I'm not on the list(s)...]

Folks:
        I was experiencing problems with 2.2.16 where the box would go out
        to lunch for a few seconds flushing buffer or paging at inopportune
        times (is there ever an opportune time for the box to become non-
        reponsive for 5 seconds? 8-).

        2.2.19pre3 makes the behaviour much better, but I still see ~ 2sec
        pauses at times. I'm sending this to the MM list as well, since I
        believe the poor behaviour in 2.2.16 was an MM issue... I don't
        know where the slowdowns are happening this time around.

        The box in question is running the linux-ha.org heartbeat package,
        which is a RT-scheduled, mlock()'ed process, and as such should
        get as good service as the box is able to mange. Often, under
        high disk (and/or MM) loads, the box becomes unreponsive for a
        period of time from ~ 1 sec to a high of ~ 2.8sec.

        The test is simply running a 'dd if=/dev/zero of=/u1/big-empty-file
        bs=1k count=512000 && date'. Generally, the box will sieze up around
        the same time as the the 'dd' finishes (maybe trying to exec date?).

        I'd appreciate any hints at how to reduce the non-reponsiveness
        window down as much as possible. I haven't yet looked to see if
        there is a version of the low-latency patches for 2.2.18 or 19pre,
        but I'd appreciate other ideas on tracking this down as well.

Thanks!
- --rafal

- ----
Rafal Boni rafal.boni@eDial.com
 PGP key C7D3024C, print EA49 160D F5E4 C46A 9E91 524E 11E0 7133 C7D3 024C
    Need to get a hold of me? rafal.boni@eDial.com">http://800.eDial.com/rafal.boni@eDial.com

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