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    SubjectRe: [PATCH 0/7] Reduce filesystem writeback from page reclaim v3
    On Wed, 10 Aug 2011 11:47:13 +0100
    Mel Gorman <mgorman@suse.de> wrote:

    > The new problem is that
    > reclaim has very little control over how long before a page in a
    > particular zone or container is cleaned which is discussed later.

    Confused - where was this discussed? Please tell us more about
    this problem and how it was addressed.


    Another (and somewhat interrelated) potential problem I see with this
    work is that it throws a big dependency onto kswapd. If kswapd gets
    stuck somewhere for extended periods, there's nothing there to perform
    direct writeback. This has happened in the past in weird situations
    such as kswpad getting blocked on ext3 journal commits which are
    themselves stuck for ages behind lots of writeout which itself is stuck
    behind lots of reads. That's an advantage of direct reclaim: more
    threads available.

    How forcefully has this stuff been tested with multiple disks per
    kswapd? Where one disk is overloaded-ext3-on-usb-stick?



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