From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752060AbdHGFl7 (ORCPT ); Mon, 7 Aug 2017 01:41:59 -0400 Received: from mga02.intel.com ([134.134.136.20]:8398 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751962AbdHGFlz (ORCPT ); Mon, 7 Aug 2017 01:41:55 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.41,336,1498546800"; d="scan'208";a="1202767408" From: "Huang, Ying" To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Huang Ying , Johannes Weiner , Minchan Kim , Rik van Riel , Shaohua Li , Hugh Dickins , Fengguang Wu , Tim Chen , Dave Hansen Subject: [PATCH -mm -v4 1/5] mm, swap: Add swap readahead hit statistics Date: Mon, 7 Aug 2017 13:40:34 +0800 Message-Id: <20170807054038.1843-2-ying.huang@intel.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170807054038.1843-1-ying.huang@intel.com> References: <20170807054038.1843-1-ying.huang@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Huang Ying 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" Cc: Johannes Weiner Cc: Minchan Kim Cc: Rik van Riel Cc: Shaohua Li Cc: Hugh Dickins Cc: Fengguang Wu Cc: Tim Chen Cc: Dave Hansen --- 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