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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, URIBL_BLOCKED,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 5D7B8C761A2 for ; Mon, 17 Feb 2020 11:13:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 36C6920801 for ; Mon, 17 Feb 2020 11:13:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="bKFno/da" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726823AbgBQLNJ (ORCPT ); Mon, 17 Feb 2020 06:13:09 -0500 Received: from aserp2120.oracle.com ([141.146.126.78]:34018 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728296AbgBQLNJ (ORCPT ); Mon, 17 Feb 2020 06:13:09 -0500 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 01HBD5P0105879; Mon, 17 Feb 2020 11:13:05 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references; s=corp-2020-01-29; bh=1o3fnj/omXneznfwHwJ6zDhr9rskZsg8Q4iKwqMgIYc=; b=bKFno/dacVawHw3uDWpFL7fV694kEVd86LqDNq1Yi/4uAwuwoKgcnj2OPXekrh3K/lkD +0EZqayA0EklJvuqzQxqzl5S0va0UTV86HYdZNNOQyyA2EKqRMbtBuBjYO9cTVSbG5LU vsz1cZ7Z37obWF15SioYBQt0mmfIwKQGZ/CQmokrQVYt2yrVItwOW8IDUPYMif0I7+wi 0fNN29iW5r0Xz19L8qTlJLf75avHuOCpCLVqX3R4ygFFDr+hqxyHIRzFSMonHKYp7pRJ XgJ+o8NjUSxwJyg+jX01sbFsiyX2eV+8JeLofOiODKtBpSZfiTZik8/jfleJts+rCQl7 pQ== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by aserp2120.oracle.com with ESMTP id 2y68kqqmn5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 17 Feb 2020 11:13:05 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 01HBBsou101544; Mon, 17 Feb 2020 11:12:59 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3020.oracle.com with ESMTP id 2y6tehey80-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 17 Feb 2020 11:12:59 +0000 Received: from abhmp0004.oracle.com (abhmp0004.oracle.com [141.146.116.10]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 01HBCxGP027534; Mon, 17 Feb 2020 11:12:59 GMT Received: from tp.localdomain (/39.109.145.141) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 17 Feb 2020 03:12:58 -0800 From: Anand Jain To: linux-btrfs@vger.kernel.org Cc: josef@toxicpanda.com, dsterba@suse.com Subject: [PATCH v5 2/5] btrfs: create read policy framework Date: Mon, 17 Feb 2020 19:12:42 +0800 Message-Id: <1581937965-16569-3-git-send-email-anand.jain@oracle.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1581937965-16569-1-git-send-email-anand.jain@oracle.com> References: <1581937965-16569-1-git-send-email-anand.jain@oracle.com> X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9533 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 phishscore=0 bulkscore=0 suspectscore=1 mlxscore=0 mlxlogscore=999 adultscore=92 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002170097 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9533 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 phishscore=0 spamscore=0 lowpriorityscore=0 mlxlogscore=999 malwarescore=0 priorityscore=1501 clxscore=1015 mlxscore=0 suspectscore=1 impostorscore=0 bulkscore=0 adultscore=90 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002170097 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org As of now we use %pid method to read stripped mirrored data, which means process id determines the stripe id to be read. This type of routing typically helps in a system with many small independent processes tying to read random data. On the other hand the %pid based read IO policy is inefficient because if there is a single process trying to read large data the overall disk bandwidth remains under-utilized. So this patch introduces read policy framework so that we could add more read policies, such as IO routing based on device's wait-queue or manual when we have a read-preferred device or a policy based on the target storage caching. Signed-off-by: Anand Jain Reviewed-by: Josef Bacik --- v5: Title renamed from:- btrfs: add read_policy framework Change log updated. Unnecessary comment dropped, added more where necessary. Optimize code in the switch remove duplicate code. Define BTRFS_READ_POLICY_DEFAULT dropped. Rename enum btrfs_read_policy_type to enum btrfs_read_policy. Rename BTRFS_READ_BY_PID to BTRFS_READ_POLICY_PID. v4: - v3: Declare fs_devices::readmirror as enum btrfs_readmirror_policy_type v2: Declare fs_devices::readmirror as u8 instead of atomic_t A small change in comment and change log wordings. fs/btrfs/volumes.c | 13 ++++++++++++- fs/btrfs/volumes.h | 14 ++++++++++++++ 2 files changed, 26 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 387f80656476..b6efb87bb0ae 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1209,6 +1209,7 @@ static int open_fs_devices(struct btrfs_fs_devices *fs_devices, fs_devices->opened = 1; fs_devices->latest_bdev = latest_dev->bdev; fs_devices->total_rw_bytes = 0; + fs_devices->read_policy = BTRFS_READ_POLICY_PID; out: return ret; } @@ -5358,7 +5359,17 @@ static int find_live_mirror(struct btrfs_fs_info *fs_info, else num_stripes = map->num_stripes; - preferred_mirror = first + current->pid % num_stripes; + switch (fs_info->fs_devices->read_policy) { + default: + /* + * Shouldn't happen, just warn and use pid instead of failing. + */ + btrfs_warn_rl(fs_info, + "unknown read_policy type %u, fallback to pid", + fs_info->fs_devices->read_policy); + case BTRFS_READ_POLICY_PID: + preferred_mirror = first + current->pid % num_stripes; + } if (dev_replace_is_ongoing && fs_info->dev_replace.cont_reading_from_srcdev_mode == diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h index f01552a0785e..ed2bba741b6e 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -209,6 +209,15 @@ struct btrfs_device { BTRFS_DEVICE_GETSET_FUNCS(disk_total_bytes); BTRFS_DEVICE_GETSET_FUNCS(bytes_used); +/* + * Read policies for the mirrored block groups, read picks the stripe based + * on these policies. + */ +enum btrfs_read_policy { + BTRFS_READ_POLICY_PID, + BTRFS_NR_READ_POLICY, +}; + struct btrfs_fs_devices { u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */ u8 metadata_uuid[BTRFS_FSID_SIZE]; @@ -260,6 +269,11 @@ struct btrfs_fs_devices { struct kobject *devices_kobj; struct kobject *devinfo_kobj; struct completion kobj_unregister; + + /* + * policy used to read the mirrored stripes + */ + enum btrfs_read_policy read_policy; }; #define BTRFS_BIO_INLINE_CSUM_SIZE 64 -- 1.8.3.1