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    From
    SubjectRE: [PATCH] 2.4.6-pre2 page_launder() improvements
    Date
    >
    > This patch has given excellent results on my laptop and my
    > workstation here and seems to improve kernel behaviour in tests
    > quite a bit. I can play mp3's unbuffered during moderate write
    > loads or moderately heavy IO ;)
    >
    > YMMV, please test it. If it works great for everybody I'd like
    > to get this improvement merged into the next -pre kernel.

    For the test I ran it through, it was about the same as 2.4.6-pre2 vanilla.

    The test I did can be simulated easilly enough. Apache with keepalives off.
    about 50 connections/second pulling a 10K file. Have half a gig of swap.
    Told the machine on boot that it had 64MB of RAM. Prestarted 250 apache
    children. Once everything settles down, I was about 10meg into swap and
    everything is running smoothly. So far so good. Now I figured I would push
    it a little more into swap so this being a production server, I can't really
    tell the world to make more connections so I do the next best thing and turn
    keepalives on with a timeout of 2 seconds figuring this would increase the
    number of apache children alive and push me deeper into swap. Restarted
    apache and within about 5 seconds the machine stopped responding to console
    input. top would not update the screen but the machine would respond to
    pings.

    I took it out of the load balancer and regained control in seconds. The 15
    minute load average showed somewhere over 150 with a bazillion apache
    processes. Even top -q would not update when I put it back into the
    balancer. The load average and number of processes started to increase until
    I got to some point where it would just stop providing output. Again,
    control returned within seconds after taking it out of the balancer. As far
    as I could tell, I never at any time got more than 100MB into swap.

    Your patch did seem to keep the machine alive a little longer but that is
    subjective and I have no data to back that statement up. Vanilla 2.4.6-pre2
    seemed to die off a little faster. Again, with both kernels, pings were
    fine, just no interactive at all. I was logged in over the net with no
    console so I could not see what was hogging the CPU bot it did not appear to
    be a user process. That top -q would not update tells me it was likely in
    the kernel because that runs as the highest priority user process. I just
    could not get any CPU in user space.


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