Messages in this thread | | | Date | Fri, 10 Dec 2010 10:16:19 +0900 | Subject | Re: [PATCH 3/6] mm: kswapd: Use the order that kswapd was reclaiming at for sleeping_prematurely() | From | Minchan Kim <> |
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On Thu, Dec 9, 2010 at 8:18 PM, Mel Gorman <mel@csn.ul.ie> wrote: > Before kswapd goes to sleep, it uses sleeping_prematurely() to check if > there was a race pushing a zone below its watermark. If the race > happened, it stays awake. However, balance_pgdat() can decide to reclaim > at a lower order if it decides that high-order reclaim is not working as
Could you specify "order-0" explicitly instead of "a lower order"? It makes more clear to me.
> expected. This information is not passed back to sleeping_prematurely(). > The impact is that kswapd remains awake reclaiming pages long after it > should have gone to sleep. This patch passes the adjusted order to > sleeping_prematurely and uses the same logic as balance_pgdat to decide > if it's ok to go to sleep. > > Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
A comment below.
> --- > mm/vmscan.c | 14 ++++++++++---- > 1 files changed, 10 insertions(+), 4 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index b4472a1..52e229e 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2132,7 +2132,7 @@ static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced) > } > > /* is kswapd sleeping prematurely? */ > -static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) > +static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) > { > int i; > unsigned long balanced = 0; > @@ -2142,7 +2142,7 @@ static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) > if (remaining) > return 1; > > - /* If after HZ/10, a zone is below the high mark, it's premature */ > + /* Check the watermark levels */ > for (i = 0; i < pgdat->nr_zones; i++) { > struct zone *zone = pgdat->node_zones + i; > > @@ -2427,7 +2427,13 @@ out: > } > } > > - return sc.nr_reclaimed; > + /* > + * Return the order we were reclaiming at so sleeping_prematurely() > + * makes a decision on the order we were last reclaiming at. However, > + * if another caller entered the allocator slow path while kswapd > + * was awake, order will remain at the higher level > + */ > + return order; > }
Please change return value description of balance_pgdat. "Returns the number of pages which were actually freed"
-- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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