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=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 99DD1C54FD0 for ; Thu, 23 Apr 2020 04:41:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6F78E2071C for ; Thu, 23 Apr 2020 04:41:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="ymGQm9PA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726349AbgDWElC (ORCPT ); Thu, 23 Apr 2020 00:41:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36768 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726259AbgDWElB (ORCPT ); Thu, 23 Apr 2020 00:41:01 -0400 Received: from mail-qv1-xf44.google.com (mail-qv1-xf44.google.com [IPv6:2607:f8b0:4864:20::f44]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 044D6C03C1AB for ; Wed, 22 Apr 2020 21:41:01 -0700 (PDT) Received: by mail-qv1-xf44.google.com with SMTP id v10so2239882qvr.2 for ; Wed, 22 Apr 2020 21:41:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=GhnxqN9CabrJDTRLrZH4BYssyupAS+5LbE1odxMWHKQ=; b=ymGQm9PAKUkPPMecNDR0Z7iD5NAolQZ9CFhElnv4TI/6sCmRDjJk0MfeiEe0Iti7UL i509QSKqeP+hwyppiLrTOkpartVsjD+nu4Hm2DUOhCGKhzl65Ar0nPiOmXCFCyeMJLoY FQESDpWKa3QWdsBSTt9OzSFiCOJBqWuGn5rUw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=GhnxqN9CabrJDTRLrZH4BYssyupAS+5LbE1odxMWHKQ=; b=Q9LTZ1X1LVoPCSycBUrZUW71JpaqpRz8YIwDHUgmPwIkgPkYD6i7CetQBs8ypXSfTm JPmoWoahk+1LFz8ubG8w+Iw+5A8NqCJJAKc3/2V+9fOGeVXZr8PpyLje+VIi8tQvmPYH dbNUDHaqYiqXfb4qxHUFl+Z5duKBAV045//MrCOnvYCUEYKWjNnoxDhWNoAiDIJiZfA9 PFpc87xuUZ/4rb+Qd4VOiVf8T7qG4k7pikHJyAVBSHOrHQspEVdiqKlnMkzwCvfFdf+J UMhZqNa/dErjo6bvA8vhbAdS4kKCkBUMZbt+C84mT1mD6/oTdlyr6lkdRLp3MC0SvNau MeMQ== X-Gm-Message-State: AGi0PuYI9qkHUt5+ZdsazATbNpHcrPkHJWO8B9mJ4aM/p3XdgLzLg2WS TT2trIT7kiBFik+wOXnHkAqE36sEXEg= X-Google-Smtp-Source: APiQypJuAiZWPo0bjJKUmv5REHrynKXgeGsjPCxFEpPfaWC1KSRLeDL4dCDzJRvYujqYBrXzSTJWhg== X-Received: by 2002:a0c:ed42:: with SMTP id v2mr2379627qvq.94.1587616859609; Wed, 22 Apr 2020 21:40:59 -0700 (PDT) Received: from joelaf.cam.corp.google.com ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id v62sm924150qkb.85.2020.04.22.21.40.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Apr 2020 21:40:59 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org Cc: "Joel Fernandes (Google)" , Amir Goldstein , Jan Kara , linux-fsdevel@vger.kernel.org Subject: [RFC] fs: Use slab constructor to initialize conn objects in fsnotify Date: Thu, 23 Apr 2020 00:40:50 -0400 Message-Id: <20200423044050.162093-1-joel@joelfernandes.org> X-Mailer: git-send-email 2.26.1.301.g55bc3eb7cb9-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org While reading the famous slab paper [1], I noticed that the conn->lock spinlock and conn->list hlist in fsnotify code is being initialized during every object allocation. This seems a good fit for the constructor within the slab to take advantage of the slab design. Move the initializtion to that. spin_lock_init(&conn->lock); INIT_HLIST_HEAD(&conn->list); [1] https://pdfs.semanticscholar.org/1acc/3a14da69dd240f2fbc11d00e09610263bdbd.pdf Signed-off-by: Joel Fernandes (Google) --- I've only build-tested. I am not very familiar with this code, so I kindly request the maintainers/reviewers to take a look and see if it makes sense. From what I see, the ->list is always empty during allocation. The spinlock allocation also seems unnecesary. fs/notify/fsnotify.c | 15 +++++++++++++-- fs/notify/mark.c | 2 -- 2 files changed, 13 insertions(+), 4 deletions(-) diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c index 46f2255800091..55ed450da3295 100644 --- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -385,6 +385,14 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is, } EXPORT_SYMBOL_GPL(fsnotify); +static void fsnotify_ctor(void *addr) +{ + struct fsnotify_mark_connector *conn = addr; + + spin_lock_init(&conn->lock); + INIT_HLIST_HEAD(&conn->list); +} + static __init int fsnotify_init(void) { int ret; @@ -395,8 +403,11 @@ static __init int fsnotify_init(void) if (ret) panic("initializing fsnotify_mark_srcu"); - fsnotify_mark_connector_cachep = KMEM_CACHE(fsnotify_mark_connector, - SLAB_PANIC); + fsnotify_mark_connector_cachep = + kmem_cache_create("fsnotify_mark_connector", + sizeof(struct fsnotify_mark_connector), + __alignof__(struct fsnotify_mark_connector), + SLAB_PANIC, fsnotify_ctor); return 0; } diff --git a/fs/notify/mark.c b/fs/notify/mark.c index 1d96216dffd19..d388e7f45e2ea 100644 --- a/fs/notify/mark.c +++ b/fs/notify/mark.c @@ -479,8 +479,6 @@ static int fsnotify_attach_connector_to_object(fsnotify_connp_t *connp, conn = kmem_cache_alloc(fsnotify_mark_connector_cachep, GFP_KERNEL); if (!conn) return -ENOMEM; - spin_lock_init(&conn->lock); - INIT_HLIST_HEAD(&conn->list); conn->type = type; conn->obj = connp; /* Cache fsid of filesystem containing the object */ -- 2.26.1.301.g55bc3eb7cb9-goog