From patchwork Thu Oct 29 07:54:10 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anand Jain X-Patchwork-Id: 11865515 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=-12.9 required=3.0 tests=BAYES_00,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,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 98CE2C55179 for ; Thu, 29 Oct 2020 07:55:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 54F3D20EDD for ; Thu, 29 Oct 2020 07:55:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="w7AJOexL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731680AbgJ2Hzp (ORCPT ); Thu, 29 Oct 2020 03:55:45 -0400 Received: from aserp2130.oracle.com ([141.146.126.79]:44760 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731546AbgJ2Hyg (ORCPT ); Thu, 29 Oct 2020 03:54:36 -0400 Received: from pps.filterd (aserp2130.oracle.com [127.0.0.1]) by aserp2130.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 09T7nH2r191223; Thu, 29 Oct 2020 07:54:30 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 : mime-version : content-transfer-encoding; s=corp-2020-01-29; bh=sBMYDI22kJmLJ8ON51/X5XzCELSygXrtgcHNzOJdRkM=; b=w7AJOexLXlNt548CZbqkvawrn7ldrSasBz1o/SQiS0r9RpiwyliQCqYJa7+GoUhzXXtz Kz03DR+v7L4UtvYQAO12hMpNz7IS7F298bSvIxyQGNG+bAtu9I8vZCK6b4Z/6iyezSf8 Vec8mFwceNPm2s2xQjcpyfez7sBa7C4inwcHhWbYNkbrlee0UV/JfbwhPY6QLi6+1t0T lQNEWjRYV7C67ti4Xe4O+tMhmI/Jn2TX1hXsVEZl0bW2puQ5uQHCOA/pJ/UrxblbOhUY +RMZ9MFkyBeAq/F4nBMaMiYcf+OaXSKtqr2ZogdaKH5S+Uva/a7KolSVjfbk2wgEM5qI Qg== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by aserp2130.oracle.com with ESMTP id 34c9sb3dpb-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 29 Oct 2020 07:54:30 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 09T7oONC175481; Thu, 29 Oct 2020 07:54:29 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3020.oracle.com with ESMTP id 34cx1sx01q-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 29 Oct 2020 07:54:29 +0000 Received: from abhmp0006.oracle.com (abhmp0006.oracle.com [141.146.116.12]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 09T7sSWh006325; Thu, 29 Oct 2020 07:54:28 GMT Received: from localhost.localdomain (/39.109.231.106) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 29 Oct 2020 00:54:28 -0700 From: Anand Jain To: linux-btrfs@vger.kernel.org Cc: dsterba@suse.com, josef@toxicpanda.com Subject: [PATCH 3/4] btrfs: introduce new read_policy device Date: Thu, 29 Oct 2020 15:54:10 +0800 Message-Id: <7c065ad4a3063ef2a44b26d112f776a42dd55b8a.1603938305.git.anand.jain@oracle.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9788 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 phishscore=0 bulkscore=0 suspectscore=1 malwarescore=0 mlxlogscore=999 mlxscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2010290056 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9788 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 impostorscore=0 mlxlogscore=999 malwarescore=0 lowpriorityscore=0 bulkscore=0 priorityscore=1501 spamscore=0 phishscore=0 clxscore=1015 suspectscore=1 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2010290055 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org Read-policy type 'device' and device flag 'read-preferred': The read-policy type device picks the device(s) flagged as read-preferred for reading chunks of type raid1, raid10, raid1c3 and raid1c4. A system might contain SSD, nvme, iscsi or san lun, and which are all a non-rotational device, so it is not a good idea to set the read-preferred automatically. Instead device read-policy along with the read-preferred flag provides an ability to do it manually. This advance tuning is useful in more than one situation, for example, - In heterogeneous-disk volume, it provides an ability to manually choose the low latency disks for reading. - Useful for more accurate testing. - Avoid known problematic device from reading the chunk until it is replaced (by marking the other good devices as read-preferred). Note: If the read-policy type is set to 'device', but there isn't any device which is flagged as read-preferred, then stripe 0 is used for reading. The device replace won't migrate the read-preferred flag to the new replace the target device. As of now, this is an in-memory only feature. It's pointless to set the read-preferred flag on the missing device, as IOs aren't submitted to the missing device. If there is more than one read-preferred device in a chunk, the read IO shall go to the stripe 0 as of now. Usage example: Consider a typical two disks raid1. Configure devid1 for reading. $ echo 1 > devinfo/1/read_preferred $ cat devinfo/1/read_preferred; cat devinfo/2/read_preferred 1 0 $ pwd /sys/fs/btrfs/12345678-1234-1234-1234-123456789abc $ cat read_policy; echo device > ./read_policy; cat read_policy [pid] device pid [device] Now read IOs are sent to devid 1 (sdb). $ echo 3 > /proc/sys/vm/drop_caches $ md5sum /btrfs/YkZI $ iostat -zy 1 | egrep 'sdb|sdc' (from another terminal) sdb 50.00 40048.00 0.00 40048 0 Change the read-preferred device from devid 1 to devid 2 (sdc). $ echo 0 > ./devinfo/1/read_preferred; echo 1 > ./devinfo/2/read_preferred; [ 3343.918658] BTRFS info (device sdb): reset read preferred on devid 1 (1334) [ 3343.919876] BTRFS info (device sdb): set read preferred on devid 2 (1334) $ echo 3 > /proc/sys/vm/drop_caches $ md5sum /btrfs/YkZI Further read ios are sent to devid 2 (sdc). $ iostat -zy 1 | egrep 'sdb|sdc' (from another terminal) sdc 49.00 40048.00 0.00 40048 0 Signed-off-by: Anand Jain --- fs/btrfs/sysfs.c | 3 ++- fs/btrfs/volumes.c | 22 ++++++++++++++++++++++ fs/btrfs/volumes.h | 1 + 3 files changed, 25 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index 35f4642a0468..11de4948b512 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -907,7 +907,8 @@ static bool btrfs_strmatch(const char *given, const char *golden) } /* Must follow the order as in enum btrfs_read_policy */ -static const char * const btrfs_read_policy_name[] = { "pid", "latency" }; +static const char * const btrfs_read_policy_name[] = { "pid", "latency", + "device" }; static ssize_t btrfs_read_policy_show(struct kobject *kobj, struct kobj_attribute *a, char *buf) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 70bcb9146e27..0cb7789a3199 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -5502,6 +5502,25 @@ static int btrfs_find_best_stripe(struct btrfs_fs_info *fs_info, return best_stripe; } +static int btrfs_find_read_preferred(struct map_lookup *map, int first, int num_stripe) +{ + int stripe_index; + int last = first + num_stripe; + + /* + * If there are more than one read preferred devices, then just pick the + * first found read preferred device as of now. + */ + for (stripe_index = first; stripe_index < last; stripe_index++) { + if (test_bit(BTRFS_DEV_STATE_READ_PREFERRED, + &map->stripes[stripe_index].dev->dev_state)) + return stripe_index; + } + + /* If there is no read preferred device then just use the first stripe */ + return first; +} + static int find_live_mirror(struct btrfs_fs_info *fs_info, struct map_lookup *map, int first, int dev_replace_is_ongoing) @@ -5536,6 +5555,9 @@ static int find_live_mirror(struct btrfs_fs_info *fs_info, preferred_mirror = btrfs_find_best_stripe(fs_info, map, first, num_stripes); break; + case BTRFS_READ_POLICY_DEVICE: + preferred_mirror = btrfs_find_read_preferred(map, first, num_stripes); + break; } if (dev_replace_is_ongoing && diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h index f1cbbb18f5ef..1448adb8993d 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -219,6 +219,7 @@ enum btrfs_chunk_allocation_policy { enum btrfs_read_policy { BTRFS_READ_POLICY_PID, BTRFS_READ_POLICY_LATENCY, + BTRFS_READ_POLICY_DEVICE, BTRFS_NR_READ_POLICY, };