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 X-Spam-Level: X-Spam-Status: No, score=-20.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 08A38C433F5 for ; Tue, 21 Sep 2021 16:13:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D824B6115A for ; Tue, 21 Sep 2021 16:13:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234366AbhIUQPP (ORCPT ); Tue, 21 Sep 2021 12:15:15 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:37652 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234279AbhIUQPJ (ORCPT ); Tue, 21 Sep 2021 12:15:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632240819; 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=Skz+wSCIMyvocC+cWmr1kqnk80+x9gFo8RgnyvxY9jI=; b=bI34Fs+7ApiP0wT6ko01niS4Be+t2jkB7WoVnoHUlD24nJKjYgRHaxB+OVHlHq1qolrTBf YJKzgBFIUg25J8GW30WqK3Yf5oK7Ko2DScyl0gJWzUR6uKKjGKeBIaLUxx0fQ2F/B2aCwF GVx8t8qYEAJPJg7kx6Inqm9Cf7KtUOk= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-476-liO8uBn9N9utwDmentQJaA-1; Tue, 21 Sep 2021 12:13:38 -0400 X-MC-Unique: liO8uBn9N9utwDmentQJaA-1 Received: by mail-wr1-f69.google.com with SMTP id m18-20020adfe952000000b0015b0aa32fd6so9249582wrn.12 for ; Tue, 21 Sep 2021 09:13:38 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=Skz+wSCIMyvocC+cWmr1kqnk80+x9gFo8RgnyvxY9jI=; b=T7UCay2OcWLA4B/D1UD4Bz72D87g+v8Ndgm51QknAWGWTRIBdFbpscLbBDxDkxUtC+ BZVOKIrLH5/tKwuxgeHqXyrQ54CDF0N/bDIa/95RDtYWcZpJg35nvhndgpNnvRmmhx/L cY1Emg1mkvK7UESRah4Jl05dwCcnLJ8xHZ5pAL+Qejgt5jf4MKgSblARw5ZoybW9QqqS RMOxHKJvLD4ftkkooCkFLga9Hnj/NzooKQmeo2qIpmUoV4l0m55irbbyHszj3X9c4ScO CXZjry3jmB4vSotsRFK3vckd0mdSHuEds8fJow7qOwEJkCWT2DOmHk87M1EVs7qc+cK0 TBfg== X-Gm-Message-State: AOAM531AlG0KNwm8pmhgv/wJWFQRQcHUaCqUqoNOvoPGd4YaHZ0s5Cm+ AWicsdP8KUPi2qucO1LknvehxBZiquiHta93kuMn6cnDRe/5pd1SOs38Pai4xDnC4RrjpBygDSA /sRZQqnE1Oz+iDdL5IXZ2bGVY X-Received: by 2002:a05:6000:c3:: with SMTP id q3mr35713548wrx.361.1632240817399; Tue, 21 Sep 2021 09:13:37 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwc8lfAIXvvAGBd2lf3kHl9jl9Ma+SH7iopQjrQOmNgpGD7Dcwtktf6tIufdAsdVPxyyoBuiQ== X-Received: by 2002:a05:6000:c3:: with SMTP id q3mr35713524wrx.361.1632240817263; Tue, 21 Sep 2021 09:13:37 -0700 (PDT) Received: from vian.redhat.com ([2a0c:5a80:1d03:b900:c3d1:5974:ce92:3123]) by smtp.gmail.com with ESMTPSA id t1sm19786477wrz.39.2021.09.21.09.13.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Sep 2021 09:13:37 -0700 (PDT) From: Nicolas Saenz Julienne To: akpm@linux-foundation.org, frederic@kernel.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, tglx@linutronix.de, cl@linux.com, peterz@infradead.org, juri.lelli@redhat.com, mingo@redhat.com, mtosatti@redhat.com, nilal@redhat.com, mgorman@suse.de, ppandit@redhat.com, williams@redhat.com, bigeasy@linutronix.de, anna-maria@linutronix.de, linux-rt-users@vger.kernel.org, Nicolas Saenz Julienne Subject: [PATCH 3/6] mm/swap: Allow remote LRU cache draining Date: Tue, 21 Sep 2021 18:13:21 +0200 Message-Id: <20210921161323.607817-4-nsaenzju@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210921161323.607817-1-nsaenzju@redhat.com> References: <20210921161323.607817-1-nsaenzju@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Some setups, notably NOHZ_FULL CPUs, are too busy to handle the per-cpu drain work queued by __lru_add_drain_all(). So introduce new a mechanism to remotely drain the per-cpu lists. It is made possible by using a more constraining locking scheme, which is disabled by default and can be enabled through the 'remote_pcpu_cache_access' static key. Regular users shouldn't see any functional or performance change. Upcoming patches will make use of the key. Based on previous work by Thomas Gleixner, Anna-Maria Gleixner, and Sebastian Andrzej Siewior[1]. [1] https://patchwork.kernel.org/project/linux-mm/cover/20190424111208.24459-1-bigeasy@linutronix.de/ Signed-off-by: Nicolas Saenz Julienne --- mm/swap.c | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-) diff --git a/mm/swap.c b/mm/swap.c index bcf73bd563a6..59e96a2520d5 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -915,19 +915,29 @@ inline void __lru_add_drain_all(bool force_all_cpus) WRITE_ONCE(lru_drain_gen, lru_drain_gen + 1); smp_mb(); - cpumask_clear(&has_work); - for_each_online_cpu(cpu) { - struct work_struct *work = &per_cpu(lru_add_drain_work, cpu); - - if (force_all_cpus || lru_cpu_needs_drain(cpu)) { - INIT_WORK(work, lru_add_drain_per_cpu); - queue_work_on(cpu, mm_percpu_wq, work); - __cpumask_set_cpu(cpu, &has_work); + if (static_branch_unlikely(&remote_pcpu_cache_access)) { + for_each_online_cpu(cpu) { + if (force_all_cpus || lru_cpu_needs_drain(cpu)) { + lru_cache_lock_cpu(&lru_pvecs.locks, cpu); + lru_add_drain_cpu(cpu); + lru_cache_unlock_cpu(&lru_pvecs.locks, cpu); + } + } + } else { + cpumask_clear(&has_work); + for_each_online_cpu(cpu) { + struct work_struct *work = &per_cpu(lru_add_drain_work, cpu); + + if (force_all_cpus || lru_cpu_needs_drain(cpu)) { + INIT_WORK(work, lru_add_drain_per_cpu); + queue_work_on(cpu, mm_percpu_wq, work); + __cpumask_set_cpu(cpu, &has_work); + } } - } - for_each_cpu(cpu, &has_work) - flush_work(&per_cpu(lru_add_drain_work, cpu)); + for_each_cpu(cpu, &has_work) + flush_work(&per_cpu(lru_add_drain_work, cpu)); + } done: mutex_unlock(&lock); -- 2.31.1