From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0AD552C9D for ; Wed, 1 Dec 2021 17:29:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79C38C53FCC; Wed, 1 Dec 2021 17:29:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1638379761; bh=0ua8sjOrlo4/qvPEQDZ2GG9HGYn5PGFOpEvfhuzi/ZY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cEDC1kVoi9AnYQa+c7E8VMRxkU52+htMqFdnE6X6VA38cH4TaKD0td1hqfSy416li 2n0NlcvJud1FjDgezFP9iZ3cYD3XJNBMbXkbz3tgj2YME4obdlkMN9GEPpNqJbaM2B gFJRQLwsfmfZstjq2w/t0CixmXFGidjzoCaxsxxuPwBdIRkk9HTfWmD6RA+as+Id8u Ljmb7P0Bsh4rlaHLjCnmD1CKUTsJuzjkGty/2Mwc7FFEaTKkbyg20ojcHYNyemrGe4 CygOaRyglY0aCSzItg7lHzpA02dH2H6F+WZ9P9Sgzmjz3NS2y5XUtGj7i26NB2dAa+ KbUjXdb1b8drA== Date: Wed, 1 Dec 2021 09:29:20 -0800 From: "Darrick J. Wong" To: Mel Gorman Cc: Alexey Avramov , Andrew Morton , Michal Hocko , Vlastimil Babka , Rik van Riel , Mike Galbraith , regressions@lists.linux.dev, Linux-fsdevel , Linux-MM , LKML Subject: Re: [PATCH 1/1] mm: vmscan: Reduce throttling due to a failure to make progress Message-ID: <20211201172920.GA8492@magnolia> References: <20211125151853.8540-1-mgorman@techsingularity.net> <20211127011246.7a8ac7b8@mail.inbox.lv> <20211129150117.GO3366@techsingularity.net> <20211201010348.31e99637@mail.inbox.lv> <20211130172754.GS3366@techsingularity.net> <20211201033836.4382a474@mail.inbox.lv> <20211201140005.GU3366@techsingularity.net> Precedence: bulk X-Mailing-List: regressions@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211201140005.GU3366@techsingularity.net> On Wed, Dec 01, 2021 at 02:00:05PM +0000, Mel Gorman wrote: > On Wed, Dec 01, 2021 at 03:38:36AM +0900, Alexey Avramov wrote: > > >due to the > > >underlying storage. > > > > I agree. > > > > >and send me the trace.out file please? > > > > https://drive.google.com/file/d/1FBjAmXwXakWPPjcn6K-B50S04vyySQO6/view > > > > Typical entries: > > > > Timer-10841 [006] ..... 14341.639496: mm_vmscan_throttled: nid=0 usec_timeout=100000 usect_delayed=100000 reason=VMSCAN_THROTTLE_WRITEBACK > > gmain-1246 [004] ..... 14341.639498: mm_vmscan_throttled: nid=0 usec_timeout=100000 usect_delayed=100000 reason=VMSCAN_THROTTLE_WRITEBACK > > Ok, the bulk of the stalls were for the same reason. Using a laptop with > slower storge (SSD but slower than the first laptop), the stalls were > almost all from the same reason and from one callsite -- shrink_node. > > I've included another patch below against 5.16-rc1 but it'll apply to > 5.16-rc3. Using the same test I get > > Swap off > -------- > Kernel: 5.15 > 2021-12-01 13:06:23,432: Peak values: avg10 avg60 avg300 > 2021-12-01 13:06:23,432: ----------- ------ ------ ------ > 2021-12-01 13:06:23,433: some cpu 4.72 2.68 1.25 > 2021-12-01 13:06:23,433: ----------- ------ ------ ------ > 2021-12-01 13:06:23,433: some io 7.63 3.29 1.03 > 2021-12-01 13:06:23,433: full io 4.28 1.91 0.63 > 2021-12-01 13:06:23,433: ----------- ------ ------ ------ > 2021-12-01 13:06:23,433: some memory 13.28 4.80 1.20 > 2021-12-01 13:06:23,434: full memory 12.22 4.44 1.11 > 2021-12-01 13:06:23,434: Stall times for the last 45.5s: > 2021-12-01 13:06:23,434: ----------- > 2021-12-01 13:06:23,434: some cpu 1.8s, avg 4.0% > 2021-12-01 13:06:23,435: ----------- > 2021-12-01 13:06:23,435: some io 2.9s, avg 6.5% > 2021-12-01 13:06:23,435: full io 1.8s, avg 4.0% > 2021-12-01 13:06:23,435: ----------- > 2021-12-01 13:06:23,435: some memory 4.4s, avg 9.6% > 2021-12-01 13:06:23,435: full memory 4.0s, avg 8.8% > 2021-12-01 13:06:23,435: > > Kernel: 5.16-rc1 > 2021-12-01 13:13:33,662: Peak values: avg10 avg60 avg300 > 2021-12-01 13:13:33,663: ----------- ------ ------ ------ > 2021-12-01 13:13:33,663: some cpu 1.97 1.84 0.80 > 2021-12-01 13:13:33,663: ----------- ------ ------ ------ > 2021-12-01 13:13:33,663: some io 49.60 26.97 13.26 > 2021-12-01 13:13:33,663: full io 45.91 24.56 12.13 > 2021-12-01 13:13:33,663: ----------- ------ ------ ------ > 2021-12-01 13:13:33,663: some memory 98.49 93.94 54.09 > 2021-12-01 13:13:33,663: full memory 98.49 93.75 53.82 > 2021-12-01 13:13:33,664: Stall times for the last 291.0s: > 2021-12-01 13:13:33,664: ----------- > 2021-12-01 13:13:33,664: some cpu 2.3s, avg 0.8% > 2021-12-01 13:13:33,664: ----------- > 2021-12-01 13:13:33,664: some io 57.2s, avg 19.7% > 2021-12-01 13:13:33,664: full io 52.9s, avg 18.2% > 2021-12-01 13:13:33,664: ----------- > 2021-12-01 13:13:33,664: some memory 244.8s, avg 84.1% > 2021-12-01 13:13:33,664: full memory 242.9s, avg 83.5% > 2021-12-01 13:13:33,664: > > Kernel: 5.16-rc1-v3r4 > 2021-12-01 13:16:46,910: Peak values: avg10 avg60 avg300 > 2021-12-01 13:16:46,910: ----------- ------ ------ ------ > 2021-12-01 13:16:46,910: some cpu 2.91 2.04 0.97 > 2021-12-01 13:16:46,910: ----------- ------ ------ ------ > 2021-12-01 13:16:46,910: some io 6.59 2.94 1.00 > 2021-12-01 13:16:46,910: full io 3.95 1.82 0.62 > 2021-12-01 13:16:46,910: ----------- ------ ------ ------ > 2021-12-01 13:16:46,910: some memory 10.29 3.67 0.90 > 2021-12-01 13:16:46,911: full memory 9.82 3.46 0.84 > 2021-12-01 13:16:46,911: Stall times for the last 44.4s: > 2021-12-01 13:16:46,911: ----------- > 2021-12-01 13:16:46,911: some cpu 1.2s, avg 2.7% > 2021-12-01 13:16:46,911: ----------- > 2021-12-01 13:16:46,911: some io 2.4s, avg 5.4% > 2021-12-01 13:16:46,911: full io 1.5s, avg 3.5% > 2021-12-01 13:16:46,911: ----------- > 2021-12-01 13:16:46,911: some memory 3.2s, avg 7.1% > 2021-12-01 13:16:46,911: full memory 3.0s, avg 6.7% > 2021-12-01 13:16:46,911: > > So stall times with v5.15 and with the patch are vaguely similar with > stall times for 5.16-rc1 being terrible > > Swap on > ------- > > Kernel: 5.15 > 2021-12-01 13:23:04,392: Peak values: avg10 avg60 avg300 > 2021-12-01 13:23:04,392: ----------- ------ ------ ------ > 2021-12-01 13:23:04,393: some cpu 8.02 5.19 2.93 > 2021-12-01 13:23:04,393: ----------- ------ ------ ------ > 2021-12-01 13:23:04,393: some io 77.30 61.75 37.00 > 2021-12-01 13:23:04,393: full io 62.33 50.53 29.98 > 2021-12-01 13:23:04,393: ----------- ------ ------ ------ > 2021-12-01 13:23:04,393: some memory 82.05 66.42 39.74 > 2021-12-01 13:23:04,393: full memory 73.27 57.79 34.39 > 2021-12-01 13:23:04,393: Stall times for the last 272.6s: > 2021-12-01 13:23:04,393: ----------- > 2021-12-01 13:23:04,393: some cpu 13.7s, avg 5.0% > 2021-12-01 13:23:04,393: ----------- > 2021-12-01 13:23:04,393: some io 167.4s, avg 61.4% > 2021-12-01 13:23:04,393: full io 135.0s, avg 49.5% > 2021-12-01 13:23:04,394: ----------- > 2021-12-01 13:23:04,394: some memory 180.4s, avg 66.2% > 2021-12-01 13:23:04,394: full memory 155.9s, avg 57.2% > 2021-12-01 13:23:04,394: > > Kernel: 5.16-rc1 > 2021-12-01 13:35:01,025: Peak values: avg10 avg60 avg300 > 2021-12-01 13:35:01,025: ----------- ------ ------ ------ > 2021-12-01 13:35:01,025: some cpu 4.03 2.51 1.46 > 2021-12-01 13:35:01,025: ----------- ------ ------ ------ > 2021-12-01 13:35:01,025: some io 61.02 38.02 25.97 > 2021-12-01 13:35:01,025: full io 53.30 32.69 22.18 > 2021-12-01 13:35:01,025: ----------- ------ ------ ------ > 2021-12-01 13:35:01,025: some memory 99.02 87.77 68.67 > 2021-12-01 13:35:01,025: full memory 98.66 85.18 65.45 > 2021-12-01 13:35:01,026: Stall times for the last 620.8s: > 2021-12-01 13:35:01,026: ----------- > 2021-12-01 13:35:01,026: some cpu 11.9s, avg 1.9% > 2021-12-01 13:35:01,026: ----------- > 2021-12-01 13:35:01,026: some io 182.9s, avg 29.5% > 2021-12-01 13:35:01,026: full io 156.0s, avg 25.1% > 2021-12-01 13:35:01,026: ----------- > 2021-12-01 13:35:01,026: some memory 463.1s, avg 74.6% > 2021-12-01 13:35:01,026: full memory 437.0s, avg 70.4% > 2021-12-01 13:35:01,026: > > Kernel: 5.16-rc1-v3r4 > 2021-12-01 13:42:43,066: Peak values: avg10 avg60 avg300 > 2021-12-01 13:42:43,066: ----------- ------ ------ ------ > 2021-12-01 13:42:43,066: some cpu 6.45 3.62 2.21 > 2021-12-01 13:42:43,066: ----------- ------ ------ ------ > 2021-12-01 13:42:43,066: some io 74.16 58.74 34.14 > 2021-12-01 13:42:43,066: full io 62.77 48.21 27.97 > 2021-12-01 13:42:43,066: ----------- ------ ------ ------ > 2021-12-01 13:42:43,066: some memory 78.82 62.85 36.39 > 2021-12-01 13:42:43,067: full memory 71.42 55.12 31.92 > 2021-12-01 13:42:43,067: Stall times for the last 257.2s: > 2021-12-01 13:42:43,067: ----------- > 2021-12-01 13:42:43,067: some cpu 9.9s, avg 3.9% > 2021-12-01 13:42:43,067: ----------- > 2021-12-01 13:42:43,067: some io 150.9s, avg 58.7% > 2021-12-01 13:42:43,067: full io 123.2s, avg 47.9% > 2021-12-01 13:42:43,067: ----------- > 2021-12-01 13:42:43,067: some memory 161.5s, avg 62.8% > 2021-12-01 13:42:43,067: full memory 141.6s, avg 55.1% > 2021-12-01 13:42:43,067: > > Again 5.16-rc1 stuttered badly but the new patch was comparable to 5.15. > > As my baseline figures are very different to yours due to differences in > storage, can you test the following please? I don't know if this was directed at me, but I reran my swapfile testcase on 5.16-rc3 and found that it had nearly the same runtime as it did in 5.15. --D > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index 58e744b78c2c..936dc0b6c226 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -277,6 +277,7 @@ enum vmscan_throttle_state { > VMSCAN_THROTTLE_WRITEBACK, > VMSCAN_THROTTLE_ISOLATED, > VMSCAN_THROTTLE_NOPROGRESS, > + VMSCAN_THROTTLE_CONGESTED, > NR_VMSCAN_THROTTLE, > }; > > diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h > index f25a6149d3ba..ca2e9009a651 100644 > --- a/include/trace/events/vmscan.h > +++ b/include/trace/events/vmscan.h > @@ -30,12 +30,14 @@ > #define _VMSCAN_THROTTLE_WRITEBACK (1 << VMSCAN_THROTTLE_WRITEBACK) > #define _VMSCAN_THROTTLE_ISOLATED (1 << VMSCAN_THROTTLE_ISOLATED) > #define _VMSCAN_THROTTLE_NOPROGRESS (1 << VMSCAN_THROTTLE_NOPROGRESS) > +#define _VMSCAN_THROTTLE_CONGESTED (1 << VMSCAN_THROTTLE_CONGESTED) > > #define show_throttle_flags(flags) \ > (flags) ? __print_flags(flags, "|", \ > {_VMSCAN_THROTTLE_WRITEBACK, "VMSCAN_THROTTLE_WRITEBACK"}, \ > {_VMSCAN_THROTTLE_ISOLATED, "VMSCAN_THROTTLE_ISOLATED"}, \ > - {_VMSCAN_THROTTLE_NOPROGRESS, "VMSCAN_THROTTLE_NOPROGRESS"} \ > + {_VMSCAN_THROTTLE_NOPROGRESS, "VMSCAN_THROTTLE_NOPROGRESS"}, \ > + {_VMSCAN_THROTTLE_CONGESTED, "VMSCAN_THROTTLE_CONGESTED"} \ > ) : "VMSCAN_THROTTLE_NONE" > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index fb9584641ac7..e3f2dd1e8cd9 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1021,6 +1021,39 @@ static void handle_write_error(struct address_space *mapping, > unlock_page(page); > } > > +bool skip_throttle_noprogress(pg_data_t *pgdat) > +{ > + int reclaimable = 0, write_pending = 0; > + int i; > + > + /* > + * If kswapd is disabled, reschedule if necessary but do not > + * throttle as the system is likely near OOM. > + */ > + if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES) > + return true; > + > + /* > + * If there are a lot of dirty/writeback pages then do not > + * throttle as throttling will occur when the pages cycle > + * towards the end of the LRU if still under writeback. > + */ > + for (i = 0; i < MAX_NR_ZONES; i++) { > + struct zone *zone = pgdat->node_zones + i; > + > + if (!populated_zone(zone)) > + continue; > + > + reclaimable += zone_reclaimable_pages(zone); > + write_pending += zone_page_state_snapshot(zone, > + NR_ZONE_WRITE_PENDING); > + } > + if (2 * write_pending <= reclaimable) > + return true; > + > + return false; > +} > + > void reclaim_throttle(pg_data_t *pgdat, enum vmscan_throttle_state reason) > { > wait_queue_head_t *wqh = &pgdat->reclaim_wait[reason]; > @@ -1056,8 +1089,16 @@ void reclaim_throttle(pg_data_t *pgdat, enum vmscan_throttle_state reason) > } > > break; > + case VMSCAN_THROTTLE_CONGESTED: > + fallthrough; > case VMSCAN_THROTTLE_NOPROGRESS: > - timeout = HZ/2; > + if (skip_throttle_noprogress(pgdat)) { > + cond_resched(); > + return; > + } > + > + timeout = 1; > + > break; > case VMSCAN_THROTTLE_ISOLATED: > timeout = HZ/50; > @@ -3321,7 +3362,7 @@ static void shrink_node(pg_data_t *pgdat, struct scan_control *sc) > if (!current_is_kswapd() && current_may_throttle() && > !sc->hibernation_mode && > test_bit(LRUVEC_CONGESTED, &target_lruvec->flags)) > - reclaim_throttle(pgdat, VMSCAN_THROTTLE_WRITEBACK); > + reclaim_throttle(pgdat, VMSCAN_THROTTLE_CONGESTED); > > if (should_continue_reclaim(pgdat, sc->nr_reclaimed - nr_reclaimed, > sc)) > @@ -3386,16 +3427,16 @@ static void consider_reclaim_throttle(pg_data_t *pgdat, struct scan_control *sc) > } > > /* > - * Do not throttle kswapd on NOPROGRESS as it will throttle on > - * VMSCAN_THROTTLE_WRITEBACK if there are too many pages under > - * writeback and marked for immediate reclaim at the tail of > - * the LRU. > + * Do not throttle kswapd or cgroup reclaim on NOPROGRESS as it will > + * throttle on VMSCAN_THROTTLE_WRITEBACK if there are too many pages > + * under writeback and marked for immediate reclaim at the tail of the > + * LRU. > */ > - if (current_is_kswapd()) > + if (current_is_kswapd() || cgroup_reclaim(sc)) > return; > > /* Throttle if making no progress at high prioities. */ > - if (sc->priority < DEF_PRIORITY - 2) > + if (sc->priority == 1 && !sc->nr_reclaimed) > reclaim_throttle(pgdat, VMSCAN_THROTTLE_NOPROGRESS); > } > > @@ -3415,6 +3456,7 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) > unsigned long nr_soft_scanned; > gfp_t orig_mask; > pg_data_t *last_pgdat = NULL; > + pg_data_t *first_pgdat = NULL; > > /* > * If the number of buffer_heads in the machine exceeds the maximum > @@ -3478,14 +3520,18 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) > /* need some check for avoid more shrink_zone() */ > } > > + if (!first_pgdat) > + first_pgdat = zone->zone_pgdat; > + > /* See comment about same check for global reclaim above */ > if (zone->zone_pgdat == last_pgdat) > continue; > last_pgdat = zone->zone_pgdat; > shrink_node(zone->zone_pgdat, sc); > - consider_reclaim_throttle(zone->zone_pgdat, sc); > } > > + consider_reclaim_throttle(first_pgdat, sc); > + > /* > * Restore to original mask to avoid the impact on the caller if we > * promoted it to __GFP_HIGHMEM. > > -- > Mel Gorman > SUSE Labs