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    SubjectRe: [PATCH 03/34] mm: Reduce the amount of work done when updating min_free_kbytes
    On Mon, Jul 23, 2012 at 02:38:16PM +0100, Mel Gorman wrote:
    > commit 938929f14cb595f43cd1a4e63e22d36cab1e4a1f upstream.
    >
    > Stable note: Fixes https://bugzilla.novell.com/show_bug.cgi?id=726210 .
    > Large machines with 1TB or more of RAM take a long time to boot
    > without this patch and may spew out soft lockup warnings.

    In comparing this with the upstream version, you have a few different
    coding style differences, but no real content difference. Why?

    >
    > When min_free_kbytes is updated blocks marked MIGRATE_RESERVE are
    > updated. Ordinarily, this work is unnoticable as it happens early
    > in boot. However, on large machines with 1TB of memory, this can take
    > a considerable time when NUMA distances are taken into account. The bulk
    > of the work is done by pageblock_is_reserved() which examines the
    > metadata for almost every page in the system. Currently, we are doing
    > this far more than necessary as it is only required while there are
    > still blocks to be marked MIGRATE_RESERVE. This patch significantly
    > reduces the amount of work done by setup_zone_migrate_reserve()
    > improving boot times on 1TB machines.
    >
    > [akpm@linux-foundation.org: coding-style fixes]

    I'm guessing you didn't pick these up?

    Anyway, I've taken it now as the original one from Linus's tree,
    hopefully this doesn't burn me later in the series...

    thanks,

    greg k-h


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