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    SubjectRe: [ext3][kernels >= at least] KDE going comatose when FS is under heavy write load (massive starvation)
    On Wed, 2007-05-02 at 08:53 +0200, Jens Axboe wrote:
    > On Fri, Apr 27 2007, Linus Torvalds wrote:
    > > So I do believe that we could probably do something about the IO
    > > scheduling _too_:
    > >
    > > - break up large write requests (yeah, it will make for worse IO
    > > throughput, but if make it configurable, and especially with
    > > controllers that don't have insane overheads per command, the
    > > difference between 128kB requests and 16MB requests is probably not
    > > really even noticeable - SCSI things with large per-command overheads
    > > are just stupid)
    > >
    > > Generating huge requests will automatically mean that they are
    > > "unbreakable" from an IO scheduler perspective, so it's bad for latency
    > > for other reqeusts once they've started.
    > Overlooked this one initially... We actually don't generate huge
    > requests, exactly because of that. Even if the device can do large
    > requests (most SATA disks today can do 32meg), we default to 512kB as
    > the largest one that we will build due to file system requests. It's
    > trivial to reduce that limit, see /sys/block/<dev>/queue/max_sectors_kb.
    > That controls the maximum per-request size.

    For the record, I haven't been able to stall KDE for ages with


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      Last update: 2007-05-02 09:39    [W:0.020 / U:0.352 seconds]
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