From: Kirill Tkhai Date: Tue, 5 Mar 2019 23:48:15 +0000 (-0800) Subject: mm/vmscan.c: do not allocate duplicate stack variables in shrink_page_list() X-Git-Tag: v5.4-rc1~1517^2~43 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=060f005f074791ec15e3ea111a0b0cac28abab06;p=platform%2Fkernel%2Flinux-rpi.git mm/vmscan.c: do not allocate duplicate stack variables in shrink_page_list() On path shrink_inactive_list() ---> shrink_page_list() we allocate stack variables for the statistics twice. This is completely useless, and this just consumes stack much more, then we really need. The patch kills duplicate stack variables from shrink_page_list(), and this reduce stack usage and object file size significantly: Stack usage: Before: vmscan.c:1122:22:shrink_page_list 648 static After: vmscan.c:1122:22:shrink_page_list 616 static Size of vmscan.o: text data bss dec hex filename Before: 56866 4720 128 61714 f112 mm/vmscan.o After: 56770 4720 128 61618 f0b2 mm/vmscan.o Link: http://lkml.kernel.org/r/154894900030.5211.12104993874109647641.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai Reviewed-by: Daniel Jordan Reviewed-by: Andrew Morton Acked-by: Michal Hocko Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/vmscan.c b/mm/vmscan.c index 07a68dc..209c2c7 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1106,16 +1106,9 @@ static unsigned long shrink_page_list(struct list_head *page_list, { LIST_HEAD(ret_pages); LIST_HEAD(free_pages); - int pgactivate = 0; - unsigned nr_unqueued_dirty = 0; - unsigned nr_dirty = 0; - unsigned nr_congested = 0; unsigned nr_reclaimed = 0; - unsigned nr_writeback = 0; - unsigned nr_immediate = 0; - unsigned nr_ref_keep = 0; - unsigned nr_unmap_fail = 0; + memset(stat, 0, sizeof(*stat)); cond_resched(); while (!list_empty(page_list)) { @@ -1159,10 +1152,10 @@ static unsigned long shrink_page_list(struct list_head *page_list, */ page_check_dirty_writeback(page, &dirty, &writeback); if (dirty || writeback) - nr_dirty++; + stat->nr_dirty++; if (dirty && !writeback) - nr_unqueued_dirty++; + stat->nr_unqueued_dirty++; /* * Treat this page as congested if the underlying BDI is or if @@ -1174,7 +1167,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, if (((dirty || writeback) && mapping && inode_write_congested(mapping->host)) || (writeback && PageReclaim(page))) - nr_congested++; + stat->nr_congested++; /* * If a page at the tail of the LRU is under writeback, there @@ -1223,7 +1216,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, if (current_is_kswapd() && PageReclaim(page) && test_bit(PGDAT_WRITEBACK, &pgdat->flags)) { - nr_immediate++; + stat->nr_immediate++; goto activate_locked; /* Case 2 above */ @@ -1241,7 +1234,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, * and it's also appropriate in global reclaim. */ SetPageReclaim(page); - nr_writeback++; + stat->nr_writeback++; goto activate_locked; /* Case 3 above */ @@ -1261,7 +1254,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, case PAGEREF_ACTIVATE: goto activate_locked; case PAGEREF_KEEP: - nr_ref_keep++; + stat->nr_ref_keep++; goto keep_locked; case PAGEREF_RECLAIM: case PAGEREF_RECLAIM_CLEAN: @@ -1326,7 +1319,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, if (unlikely(PageTransHuge(page))) flags |= TTU_SPLIT_HUGE_PMD; if (!try_to_unmap(page, flags)) { - nr_unmap_fail++; + stat->nr_unmap_fail++; goto activate_locked; } } @@ -1474,7 +1467,7 @@ activate_locked: VM_BUG_ON_PAGE(PageActive(page), page); if (!PageMlocked(page)) { SetPageActive(page); - pgactivate++; + stat->nr_activate++; count_memcg_page_event(page, PGACTIVATE); } keep_locked: @@ -1489,18 +1482,8 @@ keep: free_unref_page_list(&free_pages); list_splice(&ret_pages, page_list); - count_vm_events(PGACTIVATE, pgactivate); - - if (stat) { - stat->nr_dirty = nr_dirty; - stat->nr_congested = nr_congested; - stat->nr_unqueued_dirty = nr_unqueued_dirty; - stat->nr_writeback = nr_writeback; - stat->nr_immediate = nr_immediate; - stat->nr_activate = pgactivate; - stat->nr_ref_keep = nr_ref_keep; - stat->nr_unmap_fail = nr_unmap_fail; - } + count_vm_events(PGACTIVATE, stat->nr_activate); + return nr_reclaimed; } @@ -1512,6 +1495,7 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone, .priority = DEF_PRIORITY, .may_unmap = 1, }; + struct reclaim_stat dummy_stat; unsigned long ret; struct page *page, *next; LIST_HEAD(clean_pages); @@ -1525,7 +1509,7 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone, } ret = shrink_page_list(&clean_pages, zone->zone_pgdat, &sc, - TTU_IGNORE_ACCESS, NULL, true); + TTU_IGNORE_ACCESS, &dummy_stat, true); list_splice(&clean_pages, page_list); mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE, -ret); return ret; @@ -1900,7 +1884,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, unsigned long nr_scanned; unsigned long nr_reclaimed = 0; unsigned long nr_taken; - struct reclaim_stat stat = {}; + struct reclaim_stat stat; int file = is_file_lru(lru); struct pglist_data *pgdat = lruvec_pgdat(lruvec); struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;