Subject: + mm-compaction-do-not-count-migratepages-when-unnecessary.patch added to -mm tree To: vbabka@xxxxxxx,b.zolnierkie@xxxxxxxxxxx,cl@xxxxxxxxx,iamjoonsoo.kim@xxxxxxx,mgorman@xxxxxxx,mina86@xxxxxxxxxx,minchan@xxxxxxxxxx,n-horiguchi@xxxxxxxxxxxxx,riel@xxxxxxxxxx,rientjes@xxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Wed, 07 May 2014 14:22:41 -0700 The patch titled Subject: mm/compaction: do not count migratepages when unnecessary has been added to the -mm tree. Its filename is mm-compaction-do-not-count-migratepages-when-unnecessary.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-do-not-count-migratepages-when-unnecessary.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-do-not-count-migratepages-when-unnecessary.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Vlastimil Babka <vbabka@xxxxxxx> Subject: mm/compaction: do not count migratepages when unnecessary During compaction, update_nr_listpages() has been used to count remaining non-migrated and free pages after a call to migrage_pages(). The freepages counting has become unneccessary, and it turns out that migratepages counting is also unnecessary in most cases. The only situation when it's needed to count cc->migratepages is when migrate_pages() returns with a negative error code. Otherwise, the non-negative return value is the number of pages that were not migrated, which is exactly the count of remaining pages in the cc->migratepages list. Furthermore, any non-zero count is only interesting for the tracepoint of mm_compaction_migratepages events, because after that all remaining unmigrated pages are put back and their count is set to 0. This patch therefore removes update_nr_listpages() completely, and changes the tracepoint definition so that the manual counting is done only when the tracepoint is enabled, and only when migrate_pages() returns a negative error code. Furthermore, migrate_pages() and the tracepoints won't be called when there's nothing to migrate. This potentially avoids some wasted cycles and reduces the volume of uninteresting mm_compaction_migratepages events where "nr_migrated=0 nr_failed=0". In the stress-highalloc mmtest, this was about 75% of the events. The mm_compaction_isolate_migratepages event is better for determining that nothing was isolated for migration, and this one was just duplicating the info. Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> Reviewed-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Cc: Minchan Kim <minchan@xxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx> Cc: Michal Nazarewicz <mina86@xxxxxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/trace/events/compaction.h | 26 +++++++++++++++++++---- mm/compaction.c | 31 ++++++---------------------- 2 files changed, 29 insertions(+), 28 deletions(-) diff -puN include/trace/events/compaction.h~mm-compaction-do-not-count-migratepages-when-unnecessary include/trace/events/compaction.h --- a/include/trace/events/compaction.h~mm-compaction-do-not-count-migratepages-when-unnecessary +++ a/include/trace/events/compaction.h @@ -5,7 +5,9 @@ #define _TRACE_COMPACTION_H #include <linux/types.h> +#include <linux/list.h> #include <linux/tracepoint.h> +#include <linux/mm_types.h> #include <trace/events/gfpflags.h> DECLARE_EVENT_CLASS(mm_compaction_isolate_template, @@ -47,10 +49,11 @@ DEFINE_EVENT(mm_compaction_isolate_templ TRACE_EVENT(mm_compaction_migratepages, - TP_PROTO(unsigned long nr_migrated, - unsigned long nr_failed), + TP_PROTO(unsigned long nr_all, + int migrate_rc, + struct list_head *migratepages), - TP_ARGS(nr_migrated, nr_failed), + TP_ARGS(nr_all, migrate_rc, migratepages), TP_STRUCT__entry( __field(unsigned long, nr_migrated) @@ -58,7 +61,22 @@ TRACE_EVENT(mm_compaction_migratepages, ), TP_fast_assign( - __entry->nr_migrated = nr_migrated; + unsigned long nr_failed = 0; + struct page *page; + + /* + * migrate_pages() returns either a non-negative number + * with the number of pages that failed migration, or an + * error code, in which case we need to count the remaining + * pages manually + */ + if (migrate_rc >= 0) + nr_failed = migrate_rc; + else + list_for_each_entry(page, migratepages, lru) + nr_failed++; + + __entry->nr_migrated = nr_all - nr_failed; __entry->nr_failed = nr_failed; ), diff -puN mm/compaction.c~mm-compaction-do-not-count-migratepages-when-unnecessary mm/compaction.c --- a/mm/compaction.c~mm-compaction-do-not-count-migratepages-when-unnecessary +++ a/mm/compaction.c @@ -819,22 +819,6 @@ static void compaction_free(struct page cc->nr_freepages++; } -/* - * We cannot control nr_migratepages fully when migration is running as - * migrate_pages() has no knowledge of of compact_control. When migration is - * complete, we count the number of pages on the list by hand. - */ -static void update_nr_listpages(struct compact_control *cc) -{ - int nr_migratepages = 0; - struct page *page; - - list_for_each_entry(page, &cc->migratepages, lru) - nr_migratepages++; - - cc->nr_migratepages = nr_migratepages; -} - /* possible outcome of isolate_migratepages */ typedef enum { ISOLATE_ABORT, /* Abort compaction now */ @@ -1029,7 +1013,6 @@ static int compact_zone(struct zone *zon migrate_prep_local(); while ((ret = compact_finished(zone, cc)) == COMPACT_CONTINUE) { - unsigned long nr_migrate, nr_remaining; int err; switch (isolate_migratepages(zone, cc)) { @@ -1044,20 +1027,20 @@ static int compact_zone(struct zone *zon ; } - nr_migrate = cc->nr_migratepages; + if (!cc->nr_migratepages) + continue; + err = migrate_pages(&cc->migratepages, compaction_alloc, compaction_free, (unsigned long)cc, cc->mode, MR_COMPACTION); - update_nr_listpages(cc); - nr_remaining = cc->nr_migratepages; - trace_mm_compaction_migratepages(nr_migrate - nr_remaining, - nr_remaining); + trace_mm_compaction_migratepages(cc->nr_migratepages, err, + &cc->migratepages); - /* Release isolated pages not migrated */ + /* All pages were either migrated or will be released */ + cc->nr_migratepages = 0; if (err) { putback_movable_pages(&cc->migratepages); - cc->nr_migratepages = 0; /* * migrate_pages() may return -ENOMEM when scanners meet * and we want compact_finished() to detect it _ Patches currently in -mm which might be from vbabka@xxxxxxx are origin.patch mm-compactionc-isolate_freepages_block-small-tuneup.patch mm-page_alloc-prevent-migrate_reserve-pages-from-being-misplaced.patch mm-page_alloc-debug_vm-checks-for-free_list-placement-of-cma-and-reserve-pages.patch mm-page_alloc-debug_vm-checks-for-free_list-placement-of-cma-and-reserve-pages-fix.patch mm-compaction-clean-up-unused-code-lines.patch mm-compaction-cleanup-isolate_freepages.patch mm-compaction-cleanup-isolate_freepages-fix.patch mm-compaction-cleanup-isolate_freepages-fix-2.patch mm-migration-add-destination-page-freeing-callback.patch mm-compaction-return-failed-migration-target-pages-back-to-freelist.patch mm-compaction-add-per-zone-migration-pfn-cache-for-async-compaction.patch mm-compaction-embed-migration-mode-in-compact_control.patch mm-thp-avoid-excessive-compaction-latency-during-fault.patch mm-compaction-terminate-async-compaction-when-rescheduling.patch mm-compaction-do-not-count-migratepages-when-unnecessary.patch mm-compaction-avoid-rescanning-pageblocks-in-isolate_freepages.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html