Messages in this thread Patch in this message | | | From | "Huang, Ying" <> | Subject | [PATCH -mm -v4 1/5] mm, swap: Add swap readahead hit statistics | Date | Mon, 7 Aug 2017 13:40:34 +0800 |
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From: Huang Ying <ying.huang@intel.com>
The statistics for total readahead pages and total readahead hits are recorded and exported via the following sysfs interface.
/sys/kernel/mm/swap/ra_hits /sys/kernel/mm/swap/ra_total
With them, the efficiency of the swap readahead could be measured, so that the swap readahead algorithm and parameters could be tuned accordingly.
Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Tim Chen <tim.c.chen@intel.com> Cc: Dave Hansen <dave.hansen@intel.com> --- include/linux/vm_event_item.h | 2 ++ mm/swap_state.c | 9 +++++++-- mm/vmstat.c | 3 +++ 3 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h index e02820fc2861..27e3339cfd65 100644 --- a/include/linux/vm_event_item.h +++ b/include/linux/vm_event_item.h @@ -106,6 +106,8 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, VMACACHE_FIND_HITS, VMACACHE_FULL_FLUSHES, #endif + SWAP_RA, + SWAP_RA_HIT, NR_VM_EVENT_ITEMS }; diff --git a/mm/swap_state.c b/mm/swap_state.c index b68c93014f50..d1bdb31cab13 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -305,8 +305,10 @@ struct page * lookup_swap_cache(swp_entry_t entry) if (page && likely(!PageTransCompound(page))) { INC_CACHE_INFO(find_success); - if (TestClearPageReadahead(page)) + if (TestClearPageReadahead(page)) { atomic_inc(&swapin_readahead_hits); + count_vm_event(SWAP_RA_HIT); + } } INC_CACHE_INFO(find_total); @@ -516,8 +518,11 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask, gfp_mask, vma, addr, false); if (!page) continue; - if (offset != entry_offset && likely(!PageTransCompound(page))) + if (offset != entry_offset && + likely(!PageTransCompound(page))) { SetPageReadahead(page); + count_vm_event(SWAP_RA); + } put_page(page); } blk_finish_plug(&plug); diff --git a/mm/vmstat.c b/mm/vmstat.c index ba9b202e8500..4c2121a8b877 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1095,6 +1095,9 @@ const char * const vmstat_text[] = { "vmacache_find_hits", "vmacache_full_flushes", #endif + + "swap_ra", + "swap_ra_hit", #endif /* CONFIG_VM_EVENTS_COUNTERS */ }; #endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA */ -- 2.11.0
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