From patchwork Thu Apr 27 18:05:42 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe JAILLET X-Patchwork-Id: 88365 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:b0ea:0:b0:3b6:4342:cba0 with SMTP id b10csp468452vqo; Thu, 27 Apr 2023 11:56:53 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ5LooaNJhKnA8WY4P0czG2nyv1yOMFFC7yYS+UQKr/7zUn0B+jXCJLTpDMJJ51xsf5WnNxV X-Received: by 2002:a05:6a20:9597:b0:f2:8c89:cd30 with SMTP id iu23-20020a056a20959700b000f28c89cd30mr3054021pzb.13.1682621813404; Thu, 27 Apr 2023 11:56:53 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1682621813; cv=none; d=google.com; s=arc-20160816; b=jI7b+fIz2mWPsNKZtu+MQmBxgAYpdO9u4gAad7DcEvO24vhASBoWKhbeK7i06HbINl XosDhrvlmecuyO0Dyp0ZNY1/WEa+JyfxEXLp/JIZ6uOB3tPjiEXTOH2nQR7xKfYhxpET SUoDIwxvBghXO8vanItC1oWKvYK7sv9qKXjR9ItlkTJdv4li8yOkIkq9YC2s3zdfPHVl Wa644VM+HFch3WO6ck4yDz+zNarQVHrE7xsjchsKhkk+1bJoXa9nN6CzG3z7vGDkzFfD hmQFyKODVfh6hE/OR/1SVLu2BoSU1n38Cav/2ionHjk5sD9iprK0RmEcdIIrNb1p7bz9 Gi6w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :message-id:date:subject:cc:to:from:dkim-signature; bh=05s457roHVtlfYNypW2X8/+0EwbbmCegZeHOrtx9DR8=; b=ddaq3jEXF2j0cH/K6CbgCglH+P2SMBmZNUn4dKgifwCyrIPS4A+IYxBW08i0E7/UQD wMmbJWZREywx85T8A3EK4VD3Ei+3FbeqTlI6H/33OMiNMJhrnWzvm1zBUbPFQT8ogA54 wN57n/6FIZxqpL8NCSdWCEe7dtJUZD/sTO8SoZP8QN4nrysFy5Lm+BXoyuFnK8TmtL9r wIIopYOZV87QphoizJUvC5VbmIynJLia/+Lw2WIFhMfZD4OL4spLam/1c2xATIxXIePi 8jGQmYWEngdk4zrDkcJ0IO/hA4PE3QUPsL9xraTVAM5Jv6Gjcu1H+9dWLxhxI2/10j06 Ihjg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@wanadoo.fr header.s=t20230301 header.b=LkiPyXmL; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id j65-20020a638b44000000b0052004f9add5si19688501pge.551.2023.04.27.11.56.38; Thu, 27 Apr 2023 11:56:53 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@wanadoo.fr header.s=t20230301 header.b=LkiPyXmL; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229539AbjD0SFy (ORCPT + 99 others); Thu, 27 Apr 2023 14:05:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41394 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243708AbjD0SFw (ORCPT ); Thu, 27 Apr 2023 14:05:52 -0400 Received: from smtp.smtpout.orange.fr (smtp-24.smtpout.orange.fr [80.12.242.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0C7E43A91 for ; Thu, 27 Apr 2023 11:05:48 -0700 (PDT) Received: from pop-os.home ([86.243.2.178]) by smtp.orange.fr with ESMTPA id s601pK3Rr0J4ws601pkhoW; Thu, 27 Apr 2023 20:05:46 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=wanadoo.fr; s=t20230301; t=1682618747; bh=05s457roHVtlfYNypW2X8/+0EwbbmCegZeHOrtx9DR8=; h=From:To:Cc:Subject:Date; b=LkiPyXmL2zlMA/UwRMeBbsLQ+zg60jEPXuq+invSzYxMIqjcsOMYHSqLEZg/HQz5s orqf91Xnu06X72a3b8udo8vj3bvVArLWjlWnR+W2FLzZICQlXsqlXb9EbzTgkmncZE jiiDqb50dW2vVlp2rZmnOWaSE+N5zCdaKQ0G6xE5Sl23NAvANSDtt055JNTNg9D/5e +2jRcQ0dtVjgeW0HkqoeASQyhnpXOewv2PalEz3AIvXVeWkRorFkd1ukqRkEP1Zvyj ymDqhXVTR7pycsucL/Ka2nzBSGeOPixooayHLgwYSR5AgBVC+Wa0O81PcSQgnVJEIF T1SxDLhPlWIJw== X-ME-Helo: pop-os.home X-ME-Auth: Y2hyaXN0b3BoZS5qYWlsbGV0QHdhbmFkb28uZnI= X-ME-Date: Thu, 27 Apr 2023 20:05:46 +0200 X-ME-IP: 86.243.2.178 From: Christophe JAILLET To: Xiubo Li , Ilya Dryomov , Jeff Layton Cc: linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Christophe JAILLET , ceph-devel@vger.kernel.org Subject: [PATCH] ceph: Reorder fields in 'struct ceph_snapid_map' Date: Thu, 27 Apr 2023 20:05:42 +0200 Message-Id: <559c9a70419846e0cfc319505d3d5fffd45b3358.1682618727.git.christophe.jaillet@wanadoo.fr> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1764356850704637378?= X-GMAIL-MSGID: =?utf-8?q?1764356850704637378?= Group some variables based on their sizes to reduce holes. On x86_64, this shrinks the size of 'struct ceph_snapid_map' from 72 to 64 bytes. When such a structure is allocated, because of the way memory allocation works, when 72 bytes were requested, 96 bytes were allocated. So, on x86_64, this change saves 32 bytes per allocation and has the structure fit in a single cacheline. Signed-off-by: Christophe JAILLET Reviewed-by: Jeff Layton --- Using pahole Before: ====== struct ceph_snapid_map { struct rb_node node __attribute__((__aligned__(8))); /* 0 24 */ struct list_head lru; /* 24 16 */ atomic_t ref; /* 40 4 */ /* XXX 4 bytes hole, try to pack */ u64 snap; /* 48 8 */ dev_t dev; /* 56 4 */ /* XXX 4 bytes hole, try to pack */ /* --- cacheline 1 boundary (64 bytes) --- */ long unsigned int last_used; /* 64 8 */ /* size: 72, cachelines: 2, members: 6 */ /* sum members: 64, holes: 2, sum holes: 8 */ /* forced alignments: 1 */ /* last cacheline: 8 bytes */ } __attribute__((__aligned__(8))); --- fs/ceph/mds_client.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h index 0598faa50e2e..2328dbda5ab6 100644 --- a/fs/ceph/mds_client.h +++ b/fs/ceph/mds_client.h @@ -355,8 +355,8 @@ struct ceph_snapid_map { struct rb_node node; struct list_head lru; atomic_t ref; - u64 snap; dev_t dev; + u64 snap; unsigned long last_used; };