On Wed, Jun 17, 2020 at 11:55:07AM +0200, Vlastimil Babka wrote: > <SNIP> > > It makes no difference, at least on my gcc10 which seems to be smart enough to > do the right thing. But yeah, your suggestion is more readable and precise and > maybe can work better with a less smart compiler. Thanks. > > ----8<---- > From 615eea6f6abe288ffb708aa0d1bdfbeaf30a4cbd Mon Sep 17 00:00:00 2001 > From: Vlastimil Babka <vbabka@xxxxxxx> > Date: Tue, 16 Jun 2020 10:14:47 +0200 > Subject: [PATCH] mm, page_alloc: use unlikely() in task_capc() > > Hugh noted that task_capc() could use unlikely(), as most of the time there is > no capture in progress and we are in page freeing hot path. Indeed adding > unlikely() produces assembly that better matches the assumption and moves > all the tests away from the hot path. > > I have also noticed that we don't need to test for cc->direct_compaction as the > only place we set current->task_capture is compact_zone_order() which also > always sets cc->direct_compaction true. > > Suggested-by: Hugh Dickins <hughd@xxxxxxxxxx> > Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> > Acked-by: Hugh Dickins <hughd@googlecom> Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> -- Mel Gorman SUSE Labs
