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=-8.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 AAC94C4338F for ; Wed, 11 Aug 2021 14:49:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8F1D760F55 for ; Wed, 11 Aug 2021 14:49:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232705AbhHKOuH (ORCPT ); Wed, 11 Aug 2021 10:50:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34878 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232504AbhHKOuG (ORCPT ); Wed, 11 Aug 2021 10:50:06 -0400 Received: from mail-pl1-x62a.google.com (mail-pl1-x62a.google.com [IPv6:2607:f8b0:4864:20::62a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CE47FC061765 for ; Wed, 11 Aug 2021 07:49:42 -0700 (PDT) Received: by mail-pl1-x62a.google.com with SMTP id k2so2988935plk.13 for ; Wed, 11 Aug 2021 07:49:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=cDnjBmZu+OVbXaG5KDGErJI9ooCYzdcsXQzIphBgiZk=; b=gVE+g3XOeDah2oFeHf/FlsGK0oJeQOYoD71xLHyYwv0JmSwmjre5q4PIkBgPQkchhJ 8fkOjnWv/Eth0g9MTfdndrraXVQEH+JAkLnfONhYv9peGGfc4rAKj6pjc2tzTn7vx2zY GugIB9dfyeXmM1UQt2S9jUnl2e0Iv7eynpPKXVVyUcnapGULQoEBgf/kzKRXiF3HzLLT CZK5TpvkBGMiS17G1SXgBhz9X501zE6MgLqnd6Ig7YG3++QdNWCLcLKIjL4toGCJelZM xFet6NkSUz0aT+cP/zifa5AGNAdeyeDkySmlTWlt7kELp9z2NoYTRvawlFbj4lyJrJQ8 3lfg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=cDnjBmZu+OVbXaG5KDGErJI9ooCYzdcsXQzIphBgiZk=; b=RNVLG8DKNDow8yz0F8PE29vvTpPdG30HoqxIj66VMrohksveiaD8bZuHYOglzzJl2h fQ5xYcwrt/oVCV1bLYnJe87PXywwlcVqgU7c7yuiMuTRXPQJxds+2akyTFd4CEms655W w2ySPTC0iX88r3R+Ghyw6P3+7+Z7r1VF/F5q7Y3wz7pJY5FUJzP5VmvuDWe1wHohDHJy BEGTnTDp6g4m/rpIBLoayGuEncNnpt56szJlrLqaeAJNGZXqzx2TfyUP9gleJboSqd5c Uh3wtESC0HYEbMsnIroc1n85QzYyUvTEhzXpCzGCtGAvHhLGUdsxZ6qZ5pmhxvRawv8F tvNw== X-Gm-Message-State: AOAM531USP7/QhX3lBzGw0rwRR2wmLHoAubWi4RTJsRtFfykmYWfmG+U VKVWuqiRxD67TnxVjFqvNSs8fcwFf7NJ+RdLfwI+1w== X-Google-Smtp-Source: ABdhPJy8gKbQMEN57ufMIlxMjl9J81GQWv5iNmCH9MH+NbeR1Xf3RLNKdqDomo4rsSovdB5SFoqQYvaHbybkCrYUYSY= X-Received: by 2002:a63:f804:: with SMTP id n4mr79075pgh.341.1628693382413; Wed, 11 Aug 2021 07:49:42 -0700 (PDT) MIME-Version: 1.0 References: <20210811111921.85999-1-songmuchun@bytedance.com> <0d6c3e3b-c270-bb7d-c038-64ee3f0257cd@suse.cz> In-Reply-To: <0d6c3e3b-c270-bb7d-c038-64ee3f0257cd@suse.cz> From: Muchun Song Date: Wed, 11 Aug 2021 22:49:06 +0800 Message-ID: Subject: Re: [PATCH] mm: slub: remove preemption disabling from put_cpu_partial To: Vlastimil Babka Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Linux Memory Management List , LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 11, 2021 at 8:40 PM Vlastimil Babka wrote: > > On 8/11/21 1:19 PM, Muchun Song wrote: > > The commit d6e0b7fa1186 ("slub: make dead caches discard free slabs > > immediately") introduced those logic to speed up the destruction of > > per-memcg kmem caches, because kmem caches created for a memory > > cgroup are only destroyed after the last page charged to the cgroup > > is freed at that time. But since commit 9855609bde03 ("mm: memcg/slab: > > use a single set of kmem_caches for all accounted allocations), we > > do not have per-memcg kmem caches anymore. Are those code pointless? > > No, the kmem_cache->cpu_partial can be set to zero by 'echo 0 > /sys/ > > kernel/slab/*/cpu_partial'. In this case, the slab page will be put > > into cpu partial list and then moved to node list (because > > slub_cpu_partial() returns zero). However, we can skip putting the > > slab page to cpu partial list and just move it to node list directly. > > We can adjust the condition of kmem_cache_has_cpu_partial() to > > slub_cpu_partial() in __slab_free() and remove those code from > > put_cpu_partial() for simplification. > > > > Signed-off-by: Muchun Song > > Please check again current mmotm/next if this still applies, I think it > shouldn't anymore. Thanks. > You are right. I didn't see it before. I guess it was merged recently. But thanks for your reminder. 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Wed, 11 Aug 2021 07:49:42 -0700 (PDT) MIME-Version: 1.0 References: <20210811111921.85999-1-songmuchun@bytedance.com> <0d6c3e3b-c270-bb7d-c038-64ee3f0257cd@suse.cz> In-Reply-To: <0d6c3e3b-c270-bb7d-c038-64ee3f0257cd@suse.cz> From: Muchun Song Date: Wed, 11 Aug 2021 22:49:06 +0800 Message-ID: Subject: Re: [PATCH] mm: slub: remove preemption disabling from put_cpu_partial To: Vlastimil Babka Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Linux Memory Management List , LKML Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: C47263008BEB X-Stat-Signature: 6reafhtrhqdgnjbi6my3r9bxrxwhukgg Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=bytedance-com.20150623.gappssmtp.com header.s=20150623 header.b=gVE+g3XO; dmarc=pass (policy=none) header.from=bytedance.com; spf=pass (imf08.hostedemail.com: domain of songmuchun@bytedance.com designates 209.85.214.173 as permitted sender) smtp.mailfrom=songmuchun@bytedance.com X-HE-Tag: 1628693383-661170 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: On Wed, Aug 11, 2021 at 8:40 PM Vlastimil Babka wrote: > > On 8/11/21 1:19 PM, Muchun Song wrote: > > The commit d6e0b7fa1186 ("slub: make dead caches discard free slabs > > immediately") introduced those logic to speed up the destruction of > > per-memcg kmem caches, because kmem caches created for a memory > > cgroup are only destroyed after the last page charged to the cgroup > > is freed at that time. But since commit 9855609bde03 ("mm: memcg/slab: > > use a single set of kmem_caches for all accounted allocations), we > > do not have per-memcg kmem caches anymore. Are those code pointless? > > No, the kmem_cache->cpu_partial can be set to zero by 'echo 0 > /sys/ > > kernel/slab/*/cpu_partial'. In this case, the slab page will be put > > into cpu partial list and then moved to node list (because > > slub_cpu_partial() returns zero). However, we can skip putting the > > slab page to cpu partial list and just move it to node list directly. > > We can adjust the condition of kmem_cache_has_cpu_partial() to > > slub_cpu_partial() in __slab_free() and remove those code from > > put_cpu_partial() for simplification. > > > > Signed-off-by: Muchun Song > > Please check again current mmotm/next if this still applies, I think it > shouldn't anymore. Thanks. > You are right. I didn't see it before. I guess it was merged recently. But thanks for your reminder.