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    SubjectRe: [PATCH -mm 00/16] VM pageout scalability improvements (V8)
    Rik van Riel wrote:
    > On Mon, 26 May 2008 23:54:55 +0530
    > Balbir Singh <> wrote:
    >> Rik van Riel wrote:
    >>> On large memory systems, the VM can spend way too much time scanning
    >>> through pages that it cannot (or should not) evict from memory. Not
    >>> only does it use up CPU time, but it also provokes lock contention
    >>> and can leave large systems under memory presure in a catatonic state.
    >> Hi, Rik,
    >> This patchset looks good (I did a brief scan). I'll go ahead and play with it?
    >> What is a good memory size to test the patches on (to see improvements).
    > The larger, the better. One known problem with the current upstream
    > VM is large numbers of anonymous pages, or a mix of mlocked and anon
    > pages.
    > Once the system needs to swap something out, every single anon page
    > will have the referenced bit set and the system needs to do lots of
    > scanning before it can evict the first page. This scanning causes
    > multiple CPUs to pile up and things slow down exponentially and/or
    > catastrophically :)
    > Unfortunately the largest system I have access to on a regular basis
    > has "only" 16GB of RAM :(
    > I am also making 2.6.25 based kernel RPMs available with the split LRU
    > patch set, at
    > The most recently posted patches are newer, though...


    I've run into a case where with the splitvm patches the memory controller
    immediately OOMs a task in the cgroup on exceeding it's limit. I am going to try
    and find the root cause for it.

    Warm Regards,
    Balbir Singh
    Linux Technology Center

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      Last update: 2008-05-28 13:53    [W:0.025 / U:1.736 seconds]
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