From 243418e3925d5b5b0657ae54c322d43035e97eed Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Fri, 24 Sep 2021 15:43:47 -0700 Subject: mm: fs: invalidate bh_lrus for only cold path The kernel test robot reported the regression of fio.write_iops[1] with commit 8cc621d2f45d ("mm: fs: invalidate BH LRU during page migration"). Since lru_add_drain is called frequently, invalidate bh_lrus there could increase bh_lrus cache miss ratio, which needs more IO in the end. This patch moves the bh_lrus invalidation from the hot path( e.g., zap_page_range, pagevec_release) to cold path(i.e., lru_add_drain_all, lru_cache_disable). Zhengjun Xing confirmed "I test the patch, the regression reduced to -2.9%" [1] https://lore.kernel.org/lkml/20210520083144.GD14190@xsang-OptiPlex-9020/ [2] 8cc621d2f45d, mm: fs: invalidate BH LRU during page migration Link: https://lkml.kernel.org/r/20210907212347.1977686-1-minchan@kernel.org Signed-off-by: Minchan Kim Reported-by: kernel test robot Reviewed-by: Chris Goldsworthy Tested-by: "Xing, Zhengjun" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/swap.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) (limited to 'mm') diff --git a/mm/swap.c b/mm/swap.c index 897200d27dd0..af3cad4e5378 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -620,7 +620,6 @@ void lru_add_drain_cpu(int cpu) pagevec_lru_move_fn(pvec, lru_lazyfree_fn); activate_page_drain(cpu); - invalidate_bh_lrus_cpu(cpu); } /** @@ -703,6 +702,20 @@ void lru_add_drain(void) local_unlock(&lru_pvecs.lock); } +/* + * It's called from per-cpu workqueue context in SMP case so + * lru_add_drain_cpu and invalidate_bh_lrus_cpu should run on + * the same cpu. It shouldn't be a problem in !SMP case since + * the core is only one and the locks will disable preemption. + */ +static void lru_add_and_bh_lrus_drain(void) +{ + local_lock(&lru_pvecs.lock); + lru_add_drain_cpu(smp_processor_id()); + local_unlock(&lru_pvecs.lock); + invalidate_bh_lrus_cpu(); +} + void lru_add_drain_cpu_zone(struct zone *zone) { local_lock(&lru_pvecs.lock); @@ -717,7 +730,7 @@ static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work); static void lru_add_drain_per_cpu(struct work_struct *dummy) { - lru_add_drain(); + lru_add_and_bh_lrus_drain(); } /* @@ -858,7 +871,7 @@ void lru_cache_disable(void) */ __lru_add_drain_all(true); #else - lru_add_drain(); + lru_add_and_bh_lrus_drain(); #endif } -- cgit v1.2.3