From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 786A2C43334 for ; Mon, 20 Jun 2022 09:06:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240544AbiFTJGO (ORCPT ); Mon, 20 Jun 2022 05:06:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47676 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240528AbiFTJGE (ORCPT ); Mon, 20 Jun 2022 05:06:04 -0400 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 87C56C44 for ; Mon, 20 Jun 2022 02:06:03 -0700 (PDT) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.57]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4LRNyt0hGjzDsL9; Mon, 20 Jun 2022 17:05:26 +0800 (CST) Received: from [10.174.177.76] (10.174.177.76) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Mon, 20 Jun 2022 17:05:56 +0800 Subject: Re: [PATCH v2 3/3] mm/swap: remove swap_cache_info statistics To: "Huang, Ying" CC: , , , References: <20220608144031.829-1-linmiaohe@huawei.com> <20220608144031.829-4-linmiaohe@huawei.com> <87a6a7rc39.fsf@yhuang6-desk2.ccr.corp.intel.com> From: Miaohe Lin Message-ID: <67653af6-14a7-2017-74e7-88763f223478@huawei.com> Date: Mon, 20 Jun 2022 17:05:56 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <87a6a7rc39.fsf@yhuang6-desk2.ccr.corp.intel.com> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/6/20 16:08, Huang, Ying wrote: > Miaohe Lin writes: > >> swap_cache_info are not statistics that could be easily used to tune system >> performance because they are not easily accessile. Also they can't provide >> really useful info when OOM occurs. Remove these statistics can also help >> mitigate unneeded global swap_cache_info cacheline contention. >> >> Suggested-by: David Hildenbrand >> Signed-off-by: Miaohe Lin >> --- >> mm/swap_state.c | 17 ----------------- >> 1 file changed, 17 deletions(-) >> >> diff --git a/mm/swap_state.c b/mm/swap_state.c >> index 0a2021fc55ad..41c6a6053d5c 100644 >> --- a/mm/swap_state.c >> +++ b/mm/swap_state.c >> @@ -59,24 +59,11 @@ static bool enable_vma_readahead __read_mostly = true; >> #define GET_SWAP_RA_VAL(vma) \ >> (atomic_long_read(&(vma)->swap_readahead_info) ? : 4) >> >> -#define INC_CACHE_INFO(x) data_race(swap_cache_info.x++) >> -#define ADD_CACHE_INFO(x, nr) data_race(swap_cache_info.x += (nr)) >> - >> -static struct { >> - unsigned long add_total; >> - unsigned long del_total; >> - unsigned long find_success; >> - unsigned long find_total; >> -} swap_cache_info; >> - >> static atomic_t swapin_readahead_hits = ATOMIC_INIT(4); >> >> void show_swap_cache_info(void) >> { >> printk("%lu pages in swap cache\n", total_swapcache_pages()); >> - printk("Swap cache stats: add %lu, delete %lu, find %lu/%lu\n", >> - swap_cache_info.add_total, swap_cache_info.del_total, >> - swap_cache_info.find_success, swap_cache_info.find_total); >> printk("Free swap = %ldkB\n", >> get_nr_swap_pages() << (PAGE_SHIFT - 10)); >> printk("Total swap = %lukB\n", total_swap_pages << (PAGE_SHIFT - 10)); >> @@ -133,7 +120,6 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, >> address_space->nrpages += nr; >> __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, nr); >> __mod_lruvec_page_state(page, NR_SWAPCACHE, nr); >> - ADD_CACHE_INFO(add_total, nr); >> unlock: >> xas_unlock_irq(&xas); >> } while (xas_nomem(&xas, gfp)); >> @@ -172,7 +158,6 @@ void __delete_from_swap_cache(struct page *page, >> address_space->nrpages -= nr; >> __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, -nr); >> __mod_lruvec_page_state(page, NR_SWAPCACHE, -nr); >> - ADD_CACHE_INFO(del_total, nr); >> } >> >> /** >> @@ -348,12 +333,10 @@ struct page *lookup_swap_cache(swp_entry_t entry, struct vm_area_struct *vma, >> page = find_get_page(swap_address_space(entry), swp_offset(entry)); >> put_swap_device(si); >> >> - INC_CACHE_INFO(find_total); >> if (page) { >> bool vma_ra = swap_use_vma_readahead(); >> bool readahead; >> >> - INC_CACHE_INFO(find_success); >> /* >> * At the moment, we don't support PG_readahead for anon THP >> * so let's bail out rather than confusing the readahead stat. > > This looks reasonable. And if we want to do some statistics for swap > cache in the future, we can use BPF, that is even more convenient. BPF should be very convenient. Many thanks for reviewing! > > Acked-by: "Huang, Ying" > > Best Regards, > Huang, Ying > > . >