* [PATCH 0/2] some fix of multi-gen lru @ 2023-10-18 8:20 Huan Yang 2023-10-18 8:20 ` [PATCH 1/2] tracing: mm: multigen-lru: fix mglru trace Huan Yang 2023-10-18 8:21 ` [PATCH 2/2] mm: multi-gen lru: fix stat count Huan Yang 0 siblings, 2 replies; 9+ messages in thread From: Huan Yang @ 2023-10-18 8:20 UTC (permalink / raw) To: Yu Zhao, Steven Rostedt, Masami Hiramatsu, Andrew Morton, Huan Yang, Suren Baghdasaryan, Vlastimil Babka, linux-kernel, linux-trace-kernel, linux-mm, bpf Cc: opensource.kernel For multi-gen lru shrink_inactive trace, here are some mistake: First, nr_scanned in evict_folios means all folios which it touched in `get_nr_to_scan`(so not means nr_taken). So, we may get some info from trace like this: ``` kswapd0-89 [000] 64.887613: mm_vmscan_lru_shrink_inactive: nid=0 nr_scanned=64 nr_reclaimed=0 nr_dirty=0 nr_writeback=0 nr_congested=0 nr_immediate=0 nr_activate_anon=0 nr_activate_file=0 nr_ref_keep=0 nr_unmap_fail=0 priority=4 flags=RECLAIM_WB_FILE|RECLAIM_WB_ASYNC ``` Actually, we don't taken too much folios in shrink. This patch use difference between before sc->nr_scanned and after shrink to replace nr_taken and pass this to shrink_inactive tracing. Second, also like above info, we can't get nr_folios going to where, actually in multi-gen lru shrink, many keep by folio_update_gen when look around or other promote this folio. Third, evict_folios don't gather reclaim_stat info after shrink list, so, dirty\writeback\congested stat will miss, and we can't control LRUVEC_CONGESTED or reclaim_throttle. Patch 1 aim to resolve first and second, patch 2 resolve third. Huan Yang (2): tracing: mm: multigen-lru: fix mglru trace mm: multi-gen lru: fix stat count include/linux/vmstat.h | 2 ++ include/trace/events/vmscan.h | 8 ++++- mm/vmscan.c | 61 ++++++++++++++++++++++++++++++++--- 3 files changed, 65 insertions(+), 6 deletions(-) -- 2.34.1 ^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH 1/2] tracing: mm: multigen-lru: fix mglru trace 2023-10-18 8:20 [PATCH 0/2] some fix of multi-gen lru Huan Yang @ 2023-10-18 8:20 ` Huan Yang 2023-10-18 16:28 ` Yu Zhao 2023-10-18 8:21 ` [PATCH 2/2] mm: multi-gen lru: fix stat count Huan Yang 1 sibling, 1 reply; 9+ messages in thread From: Huan Yang @ 2023-10-18 8:20 UTC (permalink / raw) To: Yu Zhao, Steven Rostedt, Masami Hiramatsu, Andrew Morton, Suren Baghdasaryan, Huan Yang, Vlastimil Babka, linux-kernel, linux-trace-kernel, linux-mm, bpf Cc: opensource.kernel This patch add two reclaim stat: nr_promote: nr_pages shrink before promote by folio_update_gen. nr_demote: nr_pages NUMA demotion passed. And then, use correct nr_scanned which evict_folios passed into trace_mm_vmscan_lru_shrink_inactive. Mistake info like this: ``` kswapd0-89 [000] 64.887613: mm_vmscan_lru_shrink_inactive: nid=0 nr_scanned=64 nr_reclaimed=0 nr_dirty=0 nr_writeback=0 nr_congested=0 nr_immediate=0 nr_activate_anon=0 nr_activate_file=0 nr_ref_keep=0 nr_unmap_fail=0 priority=4 flags=RECLAIM_WB_FILE|RECLAIM_WB_ASYNC ``` Correct info like this: ``` <...>-9041 [006] 43.738481: mm_vmscan_lru_shrink_inactive: nid=0 nr_scanned=13 nr_reclaimed=0 nr_dirty=0 nr_writeback=0 nr_congested=0 nr_immediate=0 nr_activate_anon=9 nr_activate_file=0 nr_ref_keep=0 nr_unmap_fail=0 nr_promote=4 nr_demote=0 priority=12 flags=RECLAIM_WB_ANON|RECLAIM_WB_ASYNC ``` Signed-off-by: Huan Yang <link@vivo.com> --- include/linux/vmstat.h | 2 ++ include/trace/events/vmscan.h | 8 +++++++- mm/vmscan.c | 26 +++++++++++++++++++++----- 3 files changed, 30 insertions(+), 6 deletions(-) diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h index fed855bae6d8..ac2dd9168780 100644 --- a/include/linux/vmstat.h +++ b/include/linux/vmstat.h @@ -32,6 +32,8 @@ struct reclaim_stat { unsigned nr_ref_keep; unsigned nr_unmap_fail; unsigned nr_lazyfree_fail; + unsigned nr_promote; + unsigned nr_demote; }; enum writeback_stat_item { diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h index 1a488c30afa5..9b403824a293 100644 --- a/include/trace/events/vmscan.h +++ b/include/trace/events/vmscan.h @@ -366,6 +366,8 @@ TRACE_EVENT(mm_vmscan_lru_shrink_inactive, __field(unsigned int, nr_activate1) __field(unsigned long, nr_ref_keep) __field(unsigned long, nr_unmap_fail) + __field(unsigned long, nr_promote) + __field(unsigned long, nr_demote) __field(int, priority) __field(int, reclaim_flags) ), @@ -382,17 +384,21 @@ TRACE_EVENT(mm_vmscan_lru_shrink_inactive, __entry->nr_activate1 = stat->nr_activate[1]; __entry->nr_ref_keep = stat->nr_ref_keep; __entry->nr_unmap_fail = stat->nr_unmap_fail; + __entry->nr_promote = stat->nr_promote; + __entry->nr_demote = stat->nr_demote; __entry->priority = priority; __entry->reclaim_flags = trace_reclaim_flags(file); ), - TP_printk("nid=%d nr_scanned=%ld nr_reclaimed=%ld nr_dirty=%ld nr_writeback=%ld nr_congested=%ld nr_immediate=%ld nr_activate_anon=%d nr_activate_file=%d nr_ref_keep=%ld nr_unmap_fail=%ld priority=%d flags=%s", + TP_printk("nid=%d nr_scanned=%ld nr_reclaimed=%ld nr_dirty=%ld nr_writeback=%ld nr_congested=%ld nr_immediate=%ld nr_activate_anon=%d" + " nr_activate_file=%d nr_ref_keep=%ld nr_unmap_fail=%ld nr_promote=%ld nr_demote=%ld priority=%d flags=%s", __entry->nid, __entry->nr_scanned, __entry->nr_reclaimed, __entry->nr_dirty, __entry->nr_writeback, __entry->nr_congested, __entry->nr_immediate, __entry->nr_activate0, __entry->nr_activate1, __entry->nr_ref_keep, __entry->nr_unmap_fail, + __entry->nr_promote, __entry->nr_demote, __entry->priority, show_reclaim_flags(__entry->reclaim_flags)) ); diff --git a/mm/vmscan.c b/mm/vmscan.c index 2cc0cb41fb32..21099b9f21e0 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1063,8 +1063,10 @@ static unsigned int shrink_folio_list(struct list_head *folio_list, /* folio_update_gen() tried to promote this page? */ if (lru_gen_enabled() && !ignore_references && - folio_mapped(folio) && folio_test_referenced(folio)) + folio_mapped(folio) && folio_test_referenced(folio)) { + stat->nr_promote += nr_pages; goto keep_locked; + } /* * The number of dirty pages determines if a node is marked @@ -1193,6 +1195,7 @@ static unsigned int shrink_folio_list(struct list_head *folio_list, (thp_migration_supported() || !folio_test_large(folio))) { list_add(&folio->lru, &demote_folios); folio_unlock(folio); + stat->nr_demote += nr_pages; continue; } @@ -4495,6 +4498,8 @@ static int evict_folios(struct lruvec *lruvec, struct scan_control *sc, int swap int type; int scanned; int reclaimed; + unsigned long nr_taken = sc->nr_scanned; + unsigned int total_reclaimed = 0; LIST_HEAD(list); LIST_HEAD(clean); struct folio *folio; @@ -4521,10 +4526,7 @@ static int evict_folios(struct lruvec *lruvec, struct scan_control *sc, int swap return scanned; retry: reclaimed = shrink_folio_list(&list, pgdat, sc, &stat, false); - sc->nr_reclaimed += reclaimed; - trace_mm_vmscan_lru_shrink_inactive(pgdat->node_id, - scanned, reclaimed, &stat, sc->priority, - type ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON); + total_reclaimed += reclaimed; list_for_each_entry_safe_reverse(folio, next, &list, lru) { if (!folio_evictable(folio)) { @@ -4582,6 +4584,20 @@ static int evict_folios(struct lruvec *lruvec, struct scan_control *sc, int swap goto retry; } + /** + * MGLRU scan_folios return nr_scanned no only contains + * isolated folios. To get actually touched folios in + * shrink_folios_list, we can record last nr_scanned which + * sc saved, and sc nr_scanned will update for each folios + * which we touched. New count sub last can get right nr_taken + */ + nr_taken = sc->nr_scanned - nr_taken; + + sc->nr_reclaimed += total_reclaimed; + trace_mm_vmscan_lru_shrink_inactive(pgdat->node_id, nr_taken, + total_reclaimed, &stat, + sc->priority, type); + return scanned; } -- 2.34.1 ^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH 1/2] tracing: mm: multigen-lru: fix mglru trace 2023-10-18 8:20 ` [PATCH 1/2] tracing: mm: multigen-lru: fix mglru trace Huan Yang @ 2023-10-18 16:28 ` Yu Zhao 2023-10-19 2:24 ` Huan Yang 0 siblings, 1 reply; 9+ messages in thread From: Yu Zhao @ 2023-10-18 16:28 UTC (permalink / raw) To: Huan Yang, Jaewon Kim, Kalesh Singh Cc: Steven Rostedt, Masami Hiramatsu, Andrew Morton, Suren Baghdasaryan, Vlastimil Babka, linux-kernel, linux-trace-kernel, linux-mm, bpf, opensource.kernel On Wed, Oct 18, 2023 at 2:22 AM Huan Yang <link@vivo.com> wrote: > > This patch add two reclaim stat: > nr_promote: nr_pages shrink before promote by folio_update_gen. > nr_demote: nr_pages NUMA demotion passed. The above isn't specific to MLGRU, so they should be in a separate patchset. > And then, use correct nr_scanned which evict_folios passed into > trace_mm_vmscan_lru_shrink_inactive. > > Mistake info like this: > ``` > kswapd0-89 [000] 64.887613: mm_vmscan_lru_shrink_inactive: > nid=0 nr_scanned=64 nr_reclaimed=0 nr_dirty=0 nr_writeback=0 > nr_congested=0 nr_immediate=0 nr_activate_anon=0 nr_activate_file=0 > nr_ref_keep=0 nr_unmap_fail=0 priority=4 > flags=RECLAIM_WB_FILE|RECLAIM_WB_ASYNC > ``` > Correct info like this: > ``` > <...>-9041 [006] 43.738481: mm_vmscan_lru_shrink_inactive: > nid=0 nr_scanned=13 nr_reclaimed=0 nr_dirty=0 nr_writeback=0 > nr_congested=0 nr_immediate=0 nr_activate_anon=9 nr_activate_file=0 > nr_ref_keep=0 nr_unmap_fail=0 nr_promote=4 nr_demote=0 priority=12 > flags=RECLAIM_WB_ANON|RECLAIM_WB_ASYNC > ``` Adding Jaewon & Kalesh to take a look. ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 1/2] tracing: mm: multigen-lru: fix mglru trace 2023-10-18 16:28 ` Yu Zhao @ 2023-10-19 2:24 ` Huan Yang 0 siblings, 0 replies; 9+ messages in thread From: Huan Yang @ 2023-10-19 2:24 UTC (permalink / raw) To: Yu Zhao, Jaewon Kim, Kalesh Singh Cc: Steven Rostedt, Masami Hiramatsu, Andrew Morton, Suren Baghdasaryan, Vlastimil Babka, linux-kernel, linux-trace-kernel, linux-mm, bpf, opensource.kernel 在 2023/10/19 0:28, Yu Zhao 写道: > On Wed, Oct 18, 2023 at 2:22 AM Huan Yang <link@vivo.com> wrote: >> This patch add two reclaim stat: >> nr_promote: nr_pages shrink before promote by folio_update_gen. >> nr_demote: nr_pages NUMA demotion passed. > The above isn't specific to MLGRU, so they should be in a separate patchset. OK, nr_demote isn't MGLRU, separate is good, but, if this, nr_demote isn't need by myself, I just add this when I see this code. :) Please see nr_promote and nr_scanned fix is MGLRU need? > >> And then, use correct nr_scanned which evict_folios passed into >> trace_mm_vmscan_lru_shrink_inactive. >> >> Mistake info like this: >> ``` >> kswapd0-89 [000] 64.887613: mm_vmscan_lru_shrink_inactive: >> nid=0 nr_scanned=64 nr_reclaimed=0 nr_dirty=0 nr_writeback=0 >> nr_congested=0 nr_immediate=0 nr_activate_anon=0 nr_activate_file=0 >> nr_ref_keep=0 nr_unmap_fail=0 priority=4 >> flags=RECLAIM_WB_FILE|RECLAIM_WB_ASYNC >> ``` >> Correct info like this: >> ``` >> <...>-9041 [006] 43.738481: mm_vmscan_lru_shrink_inactive: >> nid=0 nr_scanned=13 nr_reclaimed=0 nr_dirty=0 nr_writeback=0 >> nr_congested=0 nr_immediate=0 nr_activate_anon=9 nr_activate_file=0 >> nr_ref_keep=0 nr_unmap_fail=0 nr_promote=4 nr_demote=0 priority=12 >> flags=RECLAIM_WB_ANON|RECLAIM_WB_ASYNC >> ``` > Adding Jaewon & Kalesh to take a look. Thanks, Huan ^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH 2/2] mm: multi-gen lru: fix stat count 2023-10-18 8:20 [PATCH 0/2] some fix of multi-gen lru Huan Yang 2023-10-18 8:20 ` [PATCH 1/2] tracing: mm: multigen-lru: fix mglru trace Huan Yang @ 2023-10-18 8:21 ` Huan Yang 2023-10-18 16:21 ` Yu Zhao 1 sibling, 1 reply; 9+ messages in thread From: Huan Yang @ 2023-10-18 8:21 UTC (permalink / raw) To: Yu Zhao, Steven Rostedt, Masami Hiramatsu, Andrew Morton, Huan Yang, Suren Baghdasaryan, Vlastimil Babka, linux-kernel, linux-trace-kernel, linux-mm, bpf Cc: opensource.kernel For multi-gen lru reclaim in evict_folios, like shrink_inactive_list, gather folios which isolate to reclaim, and invoke shirnk_folio_list. But, when complete shrink, it not gather shrink reclaim stat into sc, we can't get info like nr_dirty\congested in reclaim, and then control writeback, dirty number and mark as LRUVEC_CONGESTED, or just bpf trace shrink and get correct sc stat. This patch fix this by simple copy code from shrink_inactive_list when end of shrink list. Signed-off-by: Huan Yang <link@vivo.com> --- mm/vmscan.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/mm/vmscan.c b/mm/vmscan.c index 21099b9f21e0..88d1d586aea5 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4593,6 +4593,41 @@ static int evict_folios(struct lruvec *lruvec, struct scan_control *sc, int swap */ nr_taken = sc->nr_scanned - nr_taken; + /* + * If dirty folios are scanned that are not queued for IO, it + * implies that flushers are not doing their job. This can + * happen when memory pressure pushes dirty folios to the end of + * the LRU before the dirty limits are breached and the dirty + * data has expired. It can also happen when the proportion of + * dirty folios grows not through writes but through memory + * pressure reclaiming all the clean cache. And in some cases, + * the flushers simply cannot keep up with the allocation + * rate. Nudge the flusher threads in case they are asleep. + */ + if (unlikely(stat.nr_unqueued_dirty == nr_taken)) { + wakeup_flusher_threads(WB_REASON_VMSCAN); + /* + * For cgroupv1 dirty throttling is achieved by waking up + * the kernel flusher here and later waiting on folios + * which are in writeback to finish (see shrink_folio_list()). + * + * Flusher may not be able to issue writeback quickly + * enough for cgroupv1 writeback throttling to work + * on a large system. + */ + if (!writeback_throttling_sane(sc)) + reclaim_throttle(pgdat, VMSCAN_THROTTLE_WRITEBACK); + } + + sc->nr.dirty += stat.nr_dirty; + sc->nr.congested += stat.nr_congested; + sc->nr.unqueued_dirty += stat.nr_unqueued_dirty; + sc->nr.writeback += stat.nr_writeback; + sc->nr.immediate += stat.nr_immediate; + sc->nr.taken += nr_taken; + if (type) + sc->nr.file_taken += nr_taken; + sc->nr_reclaimed += total_reclaimed; trace_mm_vmscan_lru_shrink_inactive(pgdat->node_id, nr_taken, total_reclaimed, &stat, -- 2.34.1 ^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH 2/2] mm: multi-gen lru: fix stat count 2023-10-18 8:21 ` [PATCH 2/2] mm: multi-gen lru: fix stat count Huan Yang @ 2023-10-18 16:21 ` Yu Zhao 2023-10-19 2:17 ` Huan Yang 0 siblings, 1 reply; 9+ messages in thread From: Yu Zhao @ 2023-10-18 16:21 UTC (permalink / raw) To: Huan Yang Cc: Steven Rostedt, Masami Hiramatsu, Andrew Morton, Suren Baghdasaryan, Vlastimil Babka, linux-kernel, linux-trace-kernel, linux-mm, bpf, opensource.kernel On Wed, Oct 18, 2023 at 2:22 AM Huan Yang <link@vivo.com> wrote: > > For multi-gen lru reclaim in evict_folios, like shrink_inactive_list, > gather folios which isolate to reclaim, and invoke shirnk_folio_list. > > But, when complete shrink, it not gather shrink reclaim stat into sc, > we can't get info like nr_dirty\congested in reclaim, and then > control writeback, dirty number and mark as LRUVEC_CONGESTED, or > just bpf trace shrink and get correct sc stat. > > This patch fix this by simple copy code from shrink_inactive_list when > end of shrink list. MGLRU doesn't try to write back dirt file pages in the reclaim path -- it filters them out in sort_folio() and leaves them to the page writeback. (The page writeback is a dedicated component for this purpose). So there is nothing to fix. ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 2/2] mm: multi-gen lru: fix stat count 2023-10-18 16:21 ` Yu Zhao @ 2023-10-19 2:17 ` Huan Yang 2023-10-19 2:39 ` Yu Zhao 0 siblings, 1 reply; 9+ messages in thread From: Huan Yang @ 2023-10-19 2:17 UTC (permalink / raw) To: Yu Zhao Cc: Steven Rostedt, Masami Hiramatsu, Andrew Morton, Suren Baghdasaryan, Vlastimil Babka, linux-kernel, linux-trace-kernel, linux-mm, bpf, opensource.kernel Hi Yu Zhao, Thanks for your reply. 在 2023/10/19 0:21, Yu Zhao 写道: > On Wed, Oct 18, 2023 at 2:22 AM Huan Yang <link@vivo.com> wrote: >> For multi-gen lru reclaim in evict_folios, like shrink_inactive_list, >> gather folios which isolate to reclaim, and invoke shirnk_folio_list. >> >> But, when complete shrink, it not gather shrink reclaim stat into sc, >> we can't get info like nr_dirty\congested in reclaim, and then >> control writeback, dirty number and mark as LRUVEC_CONGESTED, or >> just bpf trace shrink and get correct sc stat. >> >> This patch fix this by simple copy code from shrink_inactive_list when >> end of shrink list. > MGLRU doesn't try to write back dirt file pages in the reclaim path -- > it filters them out in sort_folio() and leaves them to the page Nice to know this, sort_folio() filters some folio indeed. But, I want to know, if we touch some folio in shrink_folio_list(), may some folio become dirty or writeback even if sort_folio() filter then? > writeback. (The page writeback is a dedicated component for this > purpose). So there is nothing to fix. ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 2/2] mm: multi-gen lru: fix stat count 2023-10-19 2:17 ` Huan Yang @ 2023-10-19 2:39 ` Yu Zhao 2023-10-19 6:29 ` Huan Yang 0 siblings, 1 reply; 9+ messages in thread From: Yu Zhao @ 2023-10-19 2:39 UTC (permalink / raw) To: Huan Yang Cc: Steven Rostedt, Masami Hiramatsu, Andrew Morton, Suren Baghdasaryan, Vlastimil Babka, linux-kernel, linux-trace-kernel, linux-mm, bpf, opensource.kernel On Wed, Oct 18, 2023 at 8:17 PM Huan Yang <link@vivo.com> wrote: > > Hi Yu Zhao, > > Thanks for your reply. > > 在 2023/10/19 0:21, Yu Zhao 写道: > > On Wed, Oct 18, 2023 at 2:22 AM Huan Yang <link@vivo.com> wrote: > >> For multi-gen lru reclaim in evict_folios, like shrink_inactive_list, > >> gather folios which isolate to reclaim, and invoke shirnk_folio_list. > >> > >> But, when complete shrink, it not gather shrink reclaim stat into sc, > >> we can't get info like nr_dirty\congested in reclaim, and then > >> control writeback, dirty number and mark as LRUVEC_CONGESTED, or > >> just bpf trace shrink and get correct sc stat. > >> > >> This patch fix this by simple copy code from shrink_inactive_list when > >> end of shrink list. > > MGLRU doesn't try to write back dirt file pages in the reclaim path -- > > it filters them out in sort_folio() and leaves them to the page > Nice to know this, sort_folio() filters some folio indeed. > But, I want to know, if we touch some folio in shrink_folio_list(), may some > folio become dirty or writeback even if sort_folio() filter then? Good question: in that case MGLRU still doesn't try to write those folios back because isolate_folio() cleared PG_reclaim and shrink_folio_list() checks PG_reclaim: if (folio_test_dirty(folio)) { /* * Only kswapd can writeback filesystem folios * to avoid risk of stack overflow. But avoid * injecting inefficient single-folio I/O into * flusher writeback as much as possible: only * write folios when we've encountered many * dirty folios, and when we've already scanned * the rest of the LRU for clean folios and see * the same dirty folios again (with the reclaim * flag set). */ if (folio_is_file_lru(folio) && (!current_is_kswapd() || !folio_test_reclaim(folio) || !test_bit(PGDAT_DIRTY, &pgdat->flags))) { ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 2/2] mm: multi-gen lru: fix stat count 2023-10-19 2:39 ` Yu Zhao @ 2023-10-19 6:29 ` Huan Yang 0 siblings, 0 replies; 9+ messages in thread From: Huan Yang @ 2023-10-19 6:29 UTC (permalink / raw) To: Yu Zhao Cc: Steven Rostedt, Masami Hiramatsu, Andrew Morton, Suren Baghdasaryan, Vlastimil Babka, linux-kernel, linux-trace-kernel, linux-mm, bpf, opensource.kernel 在 2023/10/19 10:39, Yu Zhao 写道: > On Wed, Oct 18, 2023 at 8:17 PM Huan Yang <link@vivo.com> wrote: >> Hi Yu Zhao, >> >> Thanks for your reply. >> >> 在 2023/10/19 0:21, Yu Zhao 写道: >>> On Wed, Oct 18, 2023 at 2:22 AM Huan Yang <link@vivo.com> wrote: >>>> For multi-gen lru reclaim in evict_folios, like shrink_inactive_list, >>>> gather folios which isolate to reclaim, and invoke shirnk_folio_list. >>>> >>>> But, when complete shrink, it not gather shrink reclaim stat into sc, >>>> we can't get info like nr_dirty\congested in reclaim, and then >>>> control writeback, dirty number and mark as LRUVEC_CONGESTED, or >>>> just bpf trace shrink and get correct sc stat. >>>> >>>> This patch fix this by simple copy code from shrink_inactive_list when >>>> end of shrink list. >>> MGLRU doesn't try to write back dirt file pages in the reclaim path -- >>> it filters them out in sort_folio() and leaves them to the page >> Nice to know this, sort_folio() filters some folio indeed. >> But, I want to know, if we touch some folio in shrink_folio_list(), may some >> folio become dirty or writeback even if sort_folio() filter then? > Good question: in that case MGLRU still doesn't try to write those > folios back because isolate_folio() cleared PG_reclaim and > shrink_folio_list() checks PG_reclaim: Thank you too much. So, MGLRU have many diff between typic LRU reclaim. So, why don't offer MGLRU a own shrink path to avoid so many check of folio? And more think, it's nice to assign a anon/file reclaim hook into anon_vma/address_space? (Each folio, have their own shrink path, don't try check path if it no need.) > > if (folio_test_dirty(folio)) { > /* > * Only kswapd can writeback filesystem folios > * to avoid risk of stack overflow. But avoid > * injecting inefficient single-folio I/O into > * flusher writeback as much as possible: only > * write folios when we've encountered many > * dirty folios, and when we've already scanned > * the rest of the LRU for clean folios and see > * the same dirty folios again (with the reclaim > * flag set). > */ > if (folio_is_file_lru(folio) && > (!current_is_kswapd() || > !folio_test_reclaim(folio) || > !test_bit(PGDAT_DIRTY, &pgdat->flags))) { Thanks ^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2023-10-19 6:30 UTC | newest] Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2023-10-18 8:20 [PATCH 0/2] some fix of multi-gen lru Huan Yang 2023-10-18 8:20 ` [PATCH 1/2] tracing: mm: multigen-lru: fix mglru trace Huan Yang 2023-10-18 16:28 ` Yu Zhao 2023-10-19 2:24 ` Huan Yang 2023-10-18 8:21 ` [PATCH 2/2] mm: multi-gen lru: fix stat count Huan Yang 2023-10-18 16:21 ` Yu Zhao 2023-10-19 2:17 ` Huan Yang 2023-10-19 2:39 ` Yu Zhao 2023-10-19 6:29 ` Huan Yang
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