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    SubjectRe: [PATCH 5/6] mm: kswapd: Treat zone->all_unreclaimable in sleeping_prematurely similar to balance_pgdat()
    On Fri, 10 Dec 2010 10:55:32 +0000
    Mel Gorman <mel@csn.ul.ie> wrote:

    > On Fri, Dec 10, 2010 at 10:23:37AM +0900, KAMEZAWA Hiroyuki wrote:
    > > On Thu, 9 Dec 2010 11:18:19 +0000
    > > Mel Gorman <mel@csn.ul.ie> wrote:
    > >
    > > > After DEF_PRIORITY, balance_pgdat() considers all_unreclaimable zones to
    > > > be balanced but sleeping_prematurely does not. This can force kswapd to
    > > > stay awake longer than it should. This patch fixes it.
    > > >
    > > > Signed-off-by: Mel Gorman <mel@csn.ul.ie>
    > >
    > > Hmm, maybe the logic works well but I don't like very much.
    > >
    > > How about adding below instead of pgdat->node_present_pages ?
    > >
    > > static unsigned long required_balanced_pages(pgdat, classzone_idx)
    > > {
    > > unsigned long present = 0;
    > >
    > > for_each_zone_in_node(zone, pgdat) {
    > > if (zone->all_unreclaimable) /* Ignore unreclaimable zone at checking balance */
    > > continue;
    > > if (zone_idx(zone) > classzone_idx)
    > > continue;
    > > present = zone->present_pages;
    > > }
    > > return present;
    > > }
    > >
    >
    > I'm afraid I do not really understand. After your earlier comments,
    > pgdat_balanced() now looks like
    >
    > static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages,
    > int classzone_idx)
    > {
    > unsigned long present_pages = 0;
    > int i;
    >
    > for (i = 0; i <= classzone_idx; i++)
    > present_pages += pgdat->node_zones[i].present_pages;
    >
    > return balanced_pages > (present_pages >> 2);
    > }
    >
    > so the classzone is being taken into account. I'm not sure what you're
    > asking for it to be changed to. Maybe it'll be clearer after V4 comes
    > out rebased on top of mmotm.
    >

    Ah, this seems okay to me.

    Thank you.
    -Kame





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