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    SubjectRe: [PATCH v4 1/1] mm: vmscan: Reduce throttling due to a failure to make progress'
    On Tue, Feb 22, 2022 at 12:27:31PM -0500, Shuang Zhai wrote:
    > Mel Gorman wrote:
    > > On Mon, Feb 14, 2022 at 04:10:50PM -0500, Shuang Zhai wrote:
    > > > Hi Mel,
    > > >
    > > > Mel Gorman wrote:
    > > > >
    > > > > Mike Galbraith, Alexey Avramov and Darrick Wong all reported similar
    > > > > problems due to reclaim throttling for excessive lengths of time.
    > > > > In Alexey's case, a memory hog that should go OOM quickly stalls for
    > > > > several minutes before stalling. In Mike and Darrick's cases, a small
    > > > > memcg environment stalled excessively even though the system had enough
    > > > > memory overall.
    > > > >
    > > >
    > > > I recently found a regression when I tested MGLRU with fio on Linux
    > > > 5.16-rc6 [1]. After this patch was applied, I re-ran the test with Linux
    > > > 5.16, but the regression has not been fixed yet.
    > > >
    > >
    > > Am I correct in thinging that this only happens with MGLRU?
    >
    > Sorry about the confusion and let me clarify on this. The regression happens
    > on upstream Linux with the default page replacement mechanism.

    Ok, the fio command for me simply exits with an error and even if it didn't
    the test machine I have with persistent memory does not have enough pmem
    to trigger memory reclaim issues with fio. Can you do the following please?

    # echo 1 > vmscan/mm_vmscan_throttled/enable
    # cat /sys/kernel/debug/tracing/trace_pipe > trace.out

    and run the test? Compress trace.out with xz and send it to me by mail.
    If the trace is too large, send as much as you can.

    --
    Mel Gorman
    SUSE Labs

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