From patchwork Thu Sep 2 21:53:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12472765 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0E69DC43219 for ; Thu, 2 Sep 2021 21:53:30 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BCD3361153 for ; Thu, 2 Sep 2021 21:53:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org BCD3361153 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 60A226B008A; Thu, 2 Sep 2021 17:53:29 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5B99B6B00A9; Thu, 2 Sep 2021 17:53:29 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4347D8D0001; Thu, 2 Sep 2021 17:53:29 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0077.hostedemail.com [216.40.44.77]) by kanga.kvack.org (Postfix) with ESMTP id 3336E6B008A for ; Thu, 2 Sep 2021 17:53:29 -0400 (EDT) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id F3F21180E8978 for ; Thu, 2 Sep 2021 21:53:28 +0000 (UTC) X-FDA: 78543985338.09.990B71D Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf21.hostedemail.com (Postfix) with ESMTP id 9F04AD02729D for ; Thu, 2 Sep 2021 21:53:28 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id AB54C610D2; Thu, 2 Sep 2021 21:53:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1630619608; bh=One6ca/+rOEehmgvE6X2XpYQexkqM3adGMXwLS7hwX0=; h=Date:From:To:Subject:In-Reply-To:From; b=ZpTFDjmNt1MAi0oChaXBKze9RBLCMgP+LprLRhB/kkUgdkgO9BiVPeVgd5MZ3iIj7 v0op1uhxVSkZGrkYGASeYN3dB4l8iVljCJDSbCqouff001YLG6/uz0Z2P03Yv72ylE IIz37+bjVfePGsnEqZmGDRUi5W2Q5dXOR4V0oXaA= Date: Thu, 02 Sep 2021 14:53:27 -0700 From: Andrew Morton To: akpm@linux-foundation.org, hannes@cmpxchg.org, jack@suse.cz, linux-mm@kvack.org, mm-commits@vger.kernel.org, shakeelb@google.com, tj@kernel.org, torvalds@linux-foundation.org Subject: [patch 066/212] writeback: memcg: simplify cgroup_writeback_by_id Message-ID: <20210902215327.cFSNXjGv5%akpm@linux-foundation.org> In-Reply-To: <20210902144820.78957dff93d7bea620d55a89@linux-foundation.org> User-Agent: s-nail v14.8.16 Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=ZpTFDjmN; dmarc=none; spf=pass (imf21.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 9F04AD02729D X-Stat-Signature: 9g3ccosxuogahaer878gxhou6uej65r7 X-HE-Tag: 1630619608-390142 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Shakeel Butt Subject: writeback: memcg: simplify cgroup_writeback_by_id Currently cgroup_writeback_by_id calls mem_cgroup_wb_stats() to get dirty pages for a memcg. However mem_cgroup_wb_stats() does a lot more than just get the number of dirty pages. Just directly get the number of dirty pages instead of calling mem_cgroup_wb_stats(). Also cgroup_writeback_by_id() is only called for best-effort dirty flushing, so remove the unused 'nr' parameter and no need to explicitly flush memcg stats. Link: https://lkml.kernel.org/r/20210722182627.2267368-1-shakeelb@google.com Signed-off-by: Shakeel Butt Reviewed-by: Jan Kara Cc: Tejun Heo Cc: Johannes Weiner Signed-off-by: Andrew Morton --- fs/fs-writeback.c | 20 +++++++++----------- include/linux/memcontrol.h | 15 +++++++++++++++ include/linux/writeback.h | 2 +- mm/memcontrol.c | 13 +------------ 4 files changed, 26 insertions(+), 24 deletions(-) --- a/fs/fs-writeback.c~writeback-memcg-simplify-cgroup_writeback_by_id +++ a/fs/fs-writeback.c @@ -1039,20 +1039,20 @@ restart: * cgroup_writeback_by_id - initiate cgroup writeback from bdi and memcg IDs * @bdi_id: target bdi id * @memcg_id: target memcg css id - * @nr: number of pages to write, 0 for best-effort dirty flushing * @reason: reason why some writeback work initiated * @done: target wb_completion * * Initiate flush of the bdi_writeback identified by @bdi_id and @memcg_id * with the specified parameters. */ -int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, unsigned long nr, +int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, enum wb_reason reason, struct wb_completion *done) { struct backing_dev_info *bdi; struct cgroup_subsys_state *memcg_css; struct bdi_writeback *wb; struct wb_writeback_work *work; + unsigned long dirty; int ret; /* lookup bdi and memcg */ @@ -1081,24 +1081,22 @@ int cgroup_writeback_by_id(u64 bdi_id, i } /* - * If @nr is zero, the caller is attempting to write out most of + * The caller is attempting to write out most of * the currently dirty pages. Let's take the current dirty page * count and inflate it by 25% which should be large enough to * flush out most dirty pages while avoiding getting livelocked by * concurrent dirtiers. + * + * BTW the memcg stats are flushed periodically and this is best-effort + * estimation, so some potential error is ok. */ - if (!nr) { - unsigned long filepages, headroom, dirty, writeback; - - mem_cgroup_wb_stats(wb, &filepages, &headroom, &dirty, - &writeback); - nr = dirty * 10 / 8; - } + dirty = memcg_page_state(mem_cgroup_from_css(memcg_css), NR_FILE_DIRTY); + dirty = dirty * 10 / 8; /* issue the writeback work */ work = kzalloc(sizeof(*work), GFP_NOWAIT | __GFP_NOWARN); if (work) { - work->nr_pages = nr; + work->nr_pages = dirty; work->sync_mode = WB_SYNC_NONE; work->range_cyclic = 1; work->reason = reason; --- a/include/linux/memcontrol.h~writeback-memcg-simplify-cgroup_writeback_by_id +++ a/include/linux/memcontrol.h @@ -955,6 +955,16 @@ static inline void mod_memcg_state(struc local_irq_restore(flags); } +static inline unsigned long memcg_page_state(struct mem_cgroup *memcg, int idx) +{ + long x = READ_ONCE(memcg->vmstats.state[idx]); +#ifdef CONFIG_SMP + if (x < 0) + x = 0; +#endif + return x; +} + static inline unsigned long lruvec_page_state(struct lruvec *lruvec, enum node_stat_item idx) { @@ -1391,6 +1401,11 @@ static inline void mod_memcg_state(struc { } +static inline unsigned long memcg_page_state(struct mem_cgroup *memcg, int idx) +{ + return 0; +} + static inline unsigned long lruvec_page_state(struct lruvec *lruvec, enum node_stat_item idx) { --- a/include/linux/writeback.h~writeback-memcg-simplify-cgroup_writeback_by_id +++ a/include/linux/writeback.h @@ -218,7 +218,7 @@ void wbc_attach_and_unlock_inode(struct void wbc_detach_inode(struct writeback_control *wbc); void wbc_account_cgroup_owner(struct writeback_control *wbc, struct page *page, size_t bytes); -int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, unsigned long nr_pages, +int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, enum wb_reason reason, struct wb_completion *done); void cgroup_writeback_umount(void); bool cleanup_offline_cgwb(struct bdi_writeback *wb); --- a/mm/memcontrol.c~writeback-memcg-simplify-cgroup_writeback_by_id +++ a/mm/memcontrol.c @@ -646,17 +646,6 @@ void __mod_memcg_state(struct mem_cgroup } /* idx can be of type enum memcg_stat_item or node_stat_item. */ -static unsigned long memcg_page_state(struct mem_cgroup *memcg, int idx) -{ - long x = READ_ONCE(memcg->vmstats.state[idx]); -#ifdef CONFIG_SMP - if (x < 0) - x = 0; -#endif - return x; -} - -/* idx can be of type enum memcg_stat_item or node_stat_item. */ static unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx) { long x = 0; @@ -4668,7 +4657,7 @@ void mem_cgroup_flush_foreign(struct bdi atomic_read(&frn->done.cnt) == 1) { frn->at = 0; trace_flush_foreign(wb, frn->bdi_id, frn->memcg_id); - cgroup_writeback_by_id(frn->bdi_id, frn->memcg_id, 0, + cgroup_writeback_by_id(frn->bdi_id, frn->memcg_id, WB_REASON_FOREIGN_FLUSH, &frn->done); }