On Tue, 29 Jul 2014, Vlastimil Babka wrote: > > > diff --git a/include/linux/compaction.h b/include/linux/compaction.h > > > index b2e4c92..60bdf8d 100644 > > > --- a/include/linux/compaction.h > > > +++ b/include/linux/compaction.h > > > @@ -13,6 +13,14 @@ > > > /* The full zone was compacted */ > > > #define COMPACT_COMPLETE 4 > > > > > > +/* Used to signal whether compaction detected need_sched() or lock > > > contention */ > > > +/* No contention detected */ > > > +#define COMPACT_CONTENDED_NONE 0 > > > +/* Either need_sched() was true or fatal signal pending */ > > > +#define COMPACT_CONTENDED_SCHED 1 > > > +/* Zone lock or lru_lock was contended in async compaction */ > > > +#define COMPACT_CONTENDED_LOCK 2 > > > + > > > > Make this an enum? > > I tried originally, but then I would have to define it elsewhere > (mm/internal.h I think) together with compact_control. I didn't think it was > worth the extra pollution of shared header, when the return codes are also > #define and we might still get rid of need_resched() one day. >
Ok. [...] > > > @@ -2660,15 +2660,36 @@ rebalance: > > > if (!(gfp_mask & __GFP_NO_KSWAPD) || (current->flags & > > > PF_KTHREAD)) > > > migration_mode = MIGRATE_SYNC_LIGHT; > > > > > > - /* > > > - * If compaction is deferred for high-order allocations, it is because > > > - * sync compaction recently failed. In this is the case and the caller > > > - * requested a movable allocation that does not heavily disrupt the > > > - * system then fail the allocation instead of entering direct reclaim. > > > - */ > > > - if ((deferred_compaction || contended_compaction) && > > > - (gfp_mask & __GFP_NO_KSWAPD)) > > > - goto nopage; > > > > Hmm, this check will have unfortunately changed in the latest mmotm due to > > mm-thp-restructure-thp-avoidance-of-light-synchronous-migration.patch. > > I think you were changing (and moving around) a different check so there would > be merge conflicts but no semantic problem. > The idea is the same, though, I think the check should not rely on __GFP_NO_KSWAPD and rather rely on (gfp_mask & GFP_TRANSHUGE) == GFP_TRANSHUGE. In other words, all the possibilities under your new test for gfp_mask & __GFP_NO_KSWAPD are thp specific and not for the other allocators who pass __GFP_NO_KSWAPD. This patch would be a significant change in logic for those users that doesn't seem helpful. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
