From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754604AbdGYBw2 (ORCPT ); Mon, 24 Jul 2017 21:52:28 -0400 Received: from mga06.intel.com ([134.134.136.31]:23325 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753452AbdGYBwC (ORCPT ); Mon, 24 Jul 2017 21:52:02 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.40,409,1496127600"; d="scan'208";a="128988068" 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 -v3 2/6] mm, swap: Add swap readahead hit statistics Date: Tue, 25 Jul 2017 09:51:47 +0800 Message-Id: <20170725015151.19502-3-ying.huang@intel.com> X-Mailer: git-send-email 2.13.2 In-Reply-To: <20170725015151.19502-1-ying.huang@intel.com> References: <20170725015151.19502-1-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 --- mm/swap_state.c | 38 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 36 insertions(+), 2 deletions(-) diff --git a/mm/swap_state.c b/mm/swap_state.c index a13bbf504e93..8be7153967ed 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -20,6 +20,7 @@ #include #include #include +#include #include @@ -74,6 +75,15 @@ unsigned long total_swapcache_pages(void) } static atomic_t swapin_readahead_hits = ATOMIC_INIT(4); +static struct percpu_counter swapin_readahead_hits_total; +static struct percpu_counter swapin_readahead_total; + +static int __init swap_init(void) +{ + percpu_counter_init(&swapin_readahead_hits_total, 0, GFP_KERNEL); + percpu_counter_init(&swapin_readahead_total, 0, GFP_KERNEL); +} +subsys_initcall(swap_init); void show_swap_cache_info(void) { @@ -305,8 +315,10 @@ 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); + percpu_counter_inc(&swapin_readahead_hits_total); + } } INC_CACHE_INFO(find_total); @@ -516,8 +528,11 @@ 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); + percpu_counter_inc(&swapin_readahead_total); + } put_page(page); } blk_finish_plug(&plug); @@ -603,12 +618,31 @@ static ssize_t swap_cache_find_total_show( static struct kobj_attribute swap_cache_find_total_attr = __ATTR(cache_find_total, 0444, swap_cache_find_total_show, NULL); +static ssize_t swap_readahead_hits_show( + struct kobject *kobj, struct kobj_attribute *attr, char *buf) +{ + return sprintf(buf, "%lld\n", + percpu_counter_sum(&swapin_readahead_hits_total)); +} +static struct kobj_attribute swap_readahead_hits_attr = + __ATTR(ra_hits, 0444, swap_readahead_hits_show, NULL); + +static ssize_t swap_readahead_total_show( + struct kobject *kobj, struct kobj_attribute *attr, char *buf) +{ + return sprintf(buf, "%lld\n", percpu_counter_sum(&swapin_readahead_total)); +} +static struct kobj_attribute swap_readahead_total_attr = + __ATTR(ra_total, 0444, swap_readahead_total_show, NULL); + static struct attribute *swap_attrs[] = { &swap_cache_pages_attr.attr, &swap_cache_add_attr.attr, &swap_cache_del_attr.attr, &swap_cache_find_success_attr.attr, &swap_cache_find_total_attr.attr, + &swap_readahead_hits_attr.attr, + &swap_readahead_total_attr.attr, NULL, }; -- 2.13.2