From 9cca35d42eb61b69e108a17215756c46173a5e6f Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Wed, 15 Nov 2017 17:37:37 -0800 Subject: [PATCH] mm, page_alloc: enable/disable IRQs once when freeing a list of pages Patch series "Follow-up for speed up page cache truncation", v2. This series is a follow-on for Jan Kara's series "Speed up page cache truncation" series. We both ended up looking at the same problem but saw different problems based on the same data. This series builds upon his work. A variety of workloads were compared on four separate machines but each machine showed gains albeit at different levels. Minimally, some of the differences are due to NUMA where truncating data from a remote node is slower than a local node. The workloads checked were o sparse truncate microbenchmark, tiny o sparse truncate microbenchmark, large o reaim-io disk workfile o dbench4 (modified by mmtests to produce more stable results) o filebench varmail configuration for small memory size o bonnie, directory operations, working set size 2*RAM reaim-io, dbench and filebench all showed minor gains. Truncation does not dominate those workloads but were tested to ensure no other regressions. They will not be reported further. The sparse truncate microbench was written by Jan. It creates a number of files and then times how long it takes to truncate each one. The "tiny" configuraiton creates a number of files that easily fits in memory and times how long it takes to truncate files with page cache. The large configuration uses enough files to have data that is twice the size of memory and so timings there include truncating page cache and working set shadow entries in the radix tree. Patches 1-4 are the most relevant parts of this series. Patches 5-8 are optional as they are deleting code that is essentially useless but has a negligible performance impact. The changelogs have more information on performance but just for bonnie delete options, the main comparison is bonnie 4.14.0-rc5 4.14.0-rc5 4.14.0-rc5 jan-v2 vanilla mel-v2 Hmean SeqCreate ops 76.20 ( 0.00%) 75.80 ( -0.53%) 76.80 ( 0.79%) Hmean SeqCreate read 85.00 ( 0.00%) 85.00 ( 0.00%) 85.00 ( 0.00%) Hmean SeqCreate del 13752.31 ( 0.00%) 12090.23 ( -12.09%) 15304.84 ( 11.29%) Hmean RandCreate ops 76.00 ( 0.00%) 75.60 ( -0.53%) 77.00 ( 1.32%) Hmean RandCreate read 96.80 ( 0.00%) 96.80 ( 0.00%) 97.00 ( 0.21%) Hmean RandCreate del 13233.75 ( 0.00%) 11525.35 ( -12.91%) 14446.61 ( 9.16%) Jan's series is the baseline and the vanilla kernel is 12% slower where as this series on top gains another 11%. This is from a different machine than the data in the changelogs but the detailed data was not collected as there was no substantial change in v2. This patch (of 8): Freeing a list of pages current enables/disables IRQs for each page freed. This patch splits freeing a list of pages into two operations -- preparing the pages for freeing and the actual freeing. This is a tradeoff - we're taking two passes of the list to free in exchange for avoiding multiple enable/disable of IRQs. sparsetruncate (tiny) 4.14.0-rc4 4.14.0-rc4 janbatch-v1r1 oneirq-v1r1 Min Time 149.00 ( 0.00%) 141.00 ( 5.37%) 1st-qrtle Time 150.00 ( 0.00%) 142.00 ( 5.33%) 2nd-qrtle Time 151.00 ( 0.00%) 142.00 ( 5.96%) 3rd-qrtle Time 151.00 ( 0.00%) 143.00 ( 5.30%) Max-90% Time 153.00 ( 0.00%) 144.00 ( 5.88%) Max-95% Time 155.00 ( 0.00%) 147.00 ( 5.16%) Max-99% Time 201.00 ( 0.00%) 195.00 ( 2.99%) Max Time 236.00 ( 0.00%) 230.00 ( 2.54%) Amean Time 152.65 ( 0.00%) 144.37 ( 5.43%) Stddev Time 9.78 ( 0.00%) 10.44 ( -6.72%) Coeff Time 6.41 ( 0.00%) 7.23 ( -12.84%) Best99%Amean Time 152.07 ( 0.00%) 143.72 ( 5.50%) Best95%Amean Time 150.75 ( 0.00%) 142.37 ( 5.56%) Best90%Amean Time 150.59 ( 0.00%) 142.19 ( 5.58%) Best75%Amean Time 150.36 ( 0.00%) 141.92 ( 5.61%) Best50%Amean Time 150.04 ( 0.00%) 141.69 ( 5.56%) Best25%Amean Time 149.85 ( 0.00%) 141.38 ( 5.65%) With a tiny number of files, each file truncated has resident page cache and it shows that time to truncate is roughtly 5-6% with some minor jitter. 4.14.0-rc4 4.14.0-rc4 janbatch-v1r1 oneirq-v1r1 Hmean SeqCreate ops 65.27 ( 0.00%) 81.86 ( 25.43%) Hmean SeqCreate read 39.48 ( 0.00%) 47.44 ( 20.16%) Hmean SeqCreate del 24963.95 ( 0.00%) 26319.99 ( 5.43%) Hmean RandCreate ops 65.47 ( 0.00%) 82.01 ( 25.26%) Hmean RandCreate read 42.04 ( 0.00%) 51.75 ( 23.09%) Hmean RandCreate del 23377.66 ( 0.00%) 23764.79 ( 1.66%) As expected, there is a small gain for the delete operation. [mgorman@techsingularity.net: use page_private and set_page_private helpers] Link: http://lkml.kernel.org/r/20171018101547.mjycw7zreb66jzpa@techsingularity.net Link: http://lkml.kernel.org/r/20171018075952.10627-2-mgorman@techsingularity.net Signed-off-by: Mel Gorman Cc: Jan Kara Cc: Andi Kleen Cc: Dave Hansen Cc: Dave Chinner Cc: Vlastimil Babka Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 60 ++++++++++++++++++++++++++++++++++++------------- 1 file changed, 45 insertions(+), 15 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ab648e359602..6a3c4a1d513f 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2611,24 +2611,26 @@ void mark_free_pages(struct zone *zone) } #endif /* CONFIG_PM */ -/* - * Free a 0-order page - * cold == true ? free a cold page : free a hot page - */ -void free_hot_cold_page(struct page *page, bool cold) +static bool free_hot_cold_page_prepare(struct page *page, unsigned long pfn) { - struct zone *zone = page_zone(page); - struct per_cpu_pages *pcp; - unsigned long flags; - unsigned long pfn = page_to_pfn(page); int migratetype; if (!free_pcp_prepare(page)) - return; + return false; migratetype = get_pfnblock_migratetype(page, pfn); set_pcppage_migratetype(page, migratetype); - local_irq_save(flags); + return true; +} + +static void free_hot_cold_page_commit(struct page *page, unsigned long pfn, + bool cold) +{ + struct zone *zone = page_zone(page); + struct per_cpu_pages *pcp; + int migratetype; + + migratetype = get_pcppage_migratetype(page); __count_vm_event(PGFREE); /* @@ -2641,7 +2643,7 @@ void free_hot_cold_page(struct page *page, bool cold) if (migratetype >= MIGRATE_PCPTYPES) { if (unlikely(is_migrate_isolate(migratetype))) { free_one_page(zone, page, pfn, 0, migratetype); - goto out; + return; } migratetype = MIGRATE_MOVABLE; } @@ -2657,8 +2659,22 @@ void free_hot_cold_page(struct page *page, bool cold) free_pcppages_bulk(zone, batch, pcp); pcp->count -= batch; } +} -out: +/* + * Free a 0-order page + * cold == true ? free a cold page : free a hot page + */ +void free_hot_cold_page(struct page *page, bool cold) +{ + unsigned long flags; + unsigned long pfn = page_to_pfn(page); + + if (!free_hot_cold_page_prepare(page, pfn)) + return; + + local_irq_save(flags); + free_hot_cold_page_commit(page, pfn, cold); local_irq_restore(flags); } @@ -2668,11 +2684,25 @@ out: void free_hot_cold_page_list(struct list_head *list, bool cold) { struct page *page, *next; + unsigned long flags, pfn; + /* Prepare pages for freeing */ list_for_each_entry_safe(page, next, list, lru) { - trace_mm_page_free_batched(page, cold); - free_hot_cold_page(page, cold); + pfn = page_to_pfn(page); + if (!free_hot_cold_page_prepare(page, pfn)) + list_del(&page->lru); + set_page_private(page, pfn); } + + local_irq_save(flags); + list_for_each_entry_safe(page, next, list, lru) { + unsigned long pfn = page_private(page); + + set_page_private(page, 0); + trace_mm_page_free_batched(page, cold); + free_hot_cold_page_commit(page, pfn, cold); + } + local_irq_restore(flags); } /*