From nobody Wed Sep 17 10:13:25 2025 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 E18AFC3DA7A for ; Tue, 20 Dec 2022 18:28:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233478AbiLTS2V (ORCPT ); Tue, 20 Dec 2022 13:28:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58264 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230026AbiLTS2F (ORCPT ); Tue, 20 Dec 2022 13:28:05 -0500 Received: from out2.migadu.com (out2.migadu.com [IPv6:2001:41d0:2:aacc::]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB0011AD8C; Tue, 20 Dec 2022 10:28:04 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1671560883; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1c+efmi7i1PNMb6NmmQf0Ro/sE7SMscFhY/KBS3yOLk=; b=Wx7bQ5ioJAD+g491R7nSJvJ8QTYMx+OPD/+3NQf2xDyjGmSAIeS5xvA6vaaypoUUowSvau T38EBM/MyoOs0D9shUHdyPMcOMxI88n+BDtB5+ZeMySUKoKja9i+0tgo8ESPYw+WmPupoG JdpUiHXhDx7tLpgzdmFRX6vTZ0dwRYM= From: Roman Gushchin To: linux-mm@kvack.org Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Shakeel Butt , Johannes Weiner , Michal Hocko , Muchun Song , Andrew Morton , Roman Gushchin Subject: [PATCH RFC 1/2] mm: kmem: optimize get_obj_cgroup_from_current() Date: Tue, 20 Dec 2022 10:27:44 -0800 Message-Id: <20221220182745.1903540-2-roman.gushchin@linux.dev> In-Reply-To: <20221220182745.1903540-1-roman.gushchin@linux.dev> References: <20221220182745.1903540-1-roman.gushchin@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Manually inline memcg_kmem_bypass() and active_memcg() to speed up get_obj_cgroup_from_current() by avoiding duplicate in_task() checks and active_memcg() readings. Also add a likely() macro to __get_obj_cgroup_from_memcg(): obj_cgroup_tryget() should succeed at almost all times except a very unlikely race with the memcg deletion path. Signed-off-by: Roman Gushchin Acked-by: Shakeel Butt --- mm/memcontrol.c | 34 ++++++++++++++-------------------- 1 file changed, 14 insertions(+), 20 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index bafd3cde4507..82828c51d2ea 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1047,19 +1047,6 @@ struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_= struct *mm) } EXPORT_SYMBOL(get_mem_cgroup_from_mm); =20 -static __always_inline bool memcg_kmem_bypass(void) -{ - /* Allow remote memcg charging from any context. */ - if (unlikely(active_memcg())) - return false; - - /* Memcg to charge can't be determined. */ - if (!in_task() || !current->mm || (current->flags & PF_KTHREAD)) - return true; - - return false; -} - /** * mem_cgroup_iter - iterate over memory cgroup hierarchy * @root: hierarchy root @@ -3004,7 +2991,7 @@ static struct obj_cgroup *__get_obj_cgroup_from_memcg= (struct mem_cgroup *memcg) =20 for (; !mem_cgroup_is_root(memcg); memcg =3D parent_mem_cgroup(memcg)) { objcg =3D rcu_dereference(memcg->objcg); - if (objcg && obj_cgroup_tryget(objcg)) + if (likely(objcg && obj_cgroup_tryget(objcg))) break; objcg =3D NULL; } @@ -3013,16 +3000,23 @@ static struct obj_cgroup *__get_obj_cgroup_from_mem= cg(struct mem_cgroup *memcg) =20 __always_inline struct obj_cgroup *get_obj_cgroup_from_current(void) { - struct obj_cgroup *objcg =3D NULL; struct mem_cgroup *memcg; + struct obj_cgroup *objcg; =20 - if (memcg_kmem_bypass()) - return NULL; + if (in_task()) { + memcg =3D current->active_memcg; + + /* Memcg to charge can't be determined. */ + if (likely(!memcg) && (!current->mm || (current->flags & PF_KTHREAD))) + return NULL; + } else { + memcg =3D this_cpu_read(int_active_memcg); + if (likely(!memcg)) + return NULL; + } =20 rcu_read_lock(); - if (unlikely(active_memcg())) - memcg =3D active_memcg(); - else + if (!memcg) memcg =3D mem_cgroup_from_task(current); objcg =3D __get_obj_cgroup_from_memcg(memcg); rcu_read_unlock(); --=20 2.39.0