On Sat, 24 Mar 2012, Rik van Riel wrote: > > Only test compaction_suitable if the kernel is built with CONFIG_COMPACTION, > otherwise the stub compaction_suitable function will always return > COMPACT_SKIPPED and send kswapd into an infinite loop. > > Signed-off-by: Rik van Riel <riel@xxxxxxxxxx> > Reported-by: Anton Blanchard <anton@xxxxxxxxx> Thank you, Anton and Rik. I never quite got around to investigating why swapping had been nearly twice as slow with linux-next on my Aspire One (with a relatively minimal config, omitting COMPACTION). That was the reason (one half of the HT cpu busy in kswapd), and this fixes it. Tested-by: Hugh Dickins <hughd@xxxxxxxxxx> > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 7658fd6..33c332b 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2946,7 +2946,8 @@ out: > continue; > > /* Would compaction fail due to lack of free memory? */ > - if (compaction_suitable(zone, order) == COMPACT_SKIPPED) > + if (COMPACTION_BUILD && > + compaction_suitable(zone, order) == COMPACT_SKIPPED) > goto loop_again; > > /* Confirm the zone is balanced for order-0 */ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>