From patchwork Wed Jan 20 07:52:05 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anand Jain X-Patchwork-Id: 12031621 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=-18.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,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 36E6DC433E6 for ; Wed, 20 Jan 2021 07:53:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EA5C223131 for ; Wed, 20 Jan 2021 07:53:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729027AbhATHxc (ORCPT ); Wed, 20 Jan 2021 02:53:32 -0500 Received: from aserp2130.oracle.com ([141.146.126.79]:54118 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729524AbhATHxU (ORCPT ); Wed, 20 Jan 2021 02:53:20 -0500 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 10K7meGU162964; Wed, 20 Jan 2021 07:52:15 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=y937VeGWFB1iJucaXFao/WtEd31mdn6dclhagdvfEgA=; b=SqIK0b7VGxLdKNT+y8GXQ6VgekgB4NQj5dDIaKwRjbz7qbL3K1vuHakTsPgdUD5qJ5EU QYMnnZ3PGvK/0vDGkft6j3rDUIoyTEydheP1g8w01hjjqDMUjEjCU+vC3yjhpYMkAmjG zDt9YUqWg9UfwSYt8a896y1vmmyfq8Fd2Gcjl4KSSUKzsJQVCNHUziLrIYp70wrhw/PH h/rDt/7+CvvaaOzil2bXNHgbhLRBri8az9Demf6vNPYDk9ISsynvAsloSW0gm9+FzLo5 hvEFaPFynMCTy+0lZWQ6jpiW50IqeJiKGGII1qtm7OXFFT8IB7spz4/3m8HRZvSYbtmr XQ== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by aserp2130.oracle.com with ESMTP id 3668qr9589-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 20 Jan 2021 07:52:15 +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 10K7nnNQ162597; Wed, 20 Jan 2021 07:52:15 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3020.oracle.com with ESMTP id 3668rdgmhe-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 20 Jan 2021 07:52:15 +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 10K7qEZW002921; Wed, 20 Jan 2021 07:52:14 GMT Received: from ca-dev104.us.oracle.com (/10.129.135.33) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 19 Jan 2021 23:52:14 -0800 From: Anand Jain To: linux-btrfs@vger.kernel.org Cc: dsterba@suse.com, josef@toxicpanda.com Subject: [PATCH v4 1/3] btrfs: add read_policy latency Date: Tue, 19 Jan 2021 23:52:05 -0800 Message-Id: <63f6f00e2ecc741efd2200c3c87b5db52c6be2fd.1611114341.git.anand.jain@oracle.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: References: MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9869 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 spamscore=0 suspectscore=0 adultscore=0 mlxlogscore=999 bulkscore=0 malwarescore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2101200043 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9869 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 mlxscore=0 suspectscore=0 lowpriorityscore=0 bulkscore=0 adultscore=0 spamscore=0 phishscore=0 priorityscore=1501 impostorscore=0 malwarescore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2101200043 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org The read policy type latency routes the read IO based on the historical average wait-time experienced by the read IOs through the individual device. This patch obtains the historical read IO stats from the kernel block layer and calculates its average. Example usage: echo "latency" > /sys/fs/btrfs/$uuid/read_policy Signed-off-by: Anand Jain Reviewed-by: Josef Bacik --- v4: For btrfs_debug_rl() use fs_info instead of device->fs_devices->fs_info. v3: The block layer commit 0d02129e76ed (block: merge struct block_device and struct hd_struct) has changed the first argument in the function part_stat_read_all() in 5.11-rc1. So the compilation will fail. This patch fixes it. Commit log updated. v2: Use btrfs_debug_rl() instead of btrfs_info_rl() It is better we have this debug until we test this on at least few hardwares. Drop the unrelated changes. Update change log. rfc->v1: Drop part_stat_read_all instead use part_stat_read Drop inflight fs/btrfs/sysfs.c | 3 ++- fs/btrfs/volumes.c | 38 ++++++++++++++++++++++++++++++++++++++ fs/btrfs/volumes.h | 2 ++ 3 files changed, 42 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index 4522a1c4cd08..7c0324fe97b2 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -915,7 +915,8 @@ static bool strmatch(const char *buffer, const char *string) return false; } -static const char * const btrfs_read_policy_name[] = { "pid" }; +/* Must follow the order as in enum btrfs_read_policy */ +static const char * const btrfs_read_policy_name[] = { "pid", "latency" }; 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 62d6a890fc50..f361f1c87eb6 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -14,6 +14,7 @@ #include #include #include +#include #include "misc.h" #include "ctree.h" #include "extent_map.h" @@ -5490,6 +5491,39 @@ int btrfs_is_parity_mirror(struct btrfs_fs_info *fs_info, u64 logical, u64 len) return ret; } +static int btrfs_find_best_stripe(struct btrfs_fs_info *fs_info, + struct map_lookup *map, int first, + int num_stripe) +{ + u64 est_wait = 0; + int best_stripe = 0; + int index; + + for (index = first; index < first + num_stripe; index++) { + u64 read_wait; + u64 avg_wait = 0; + unsigned long read_ios; + struct btrfs_device *device = map->stripes[index].dev; + + read_wait = part_stat_read(device->bdev, nsecs[READ]); + read_ios = part_stat_read(device->bdev, ios[READ]); + + if (read_wait && read_ios && read_wait >= read_ios) + avg_wait = div_u64(read_wait, read_ios); + else + btrfs_debug_rl(fs_info, + "devid: %llu avg_wait ZERO read_wait %llu read_ios %lu", + device->devid, read_wait, read_ios); + + if (est_wait == 0 || est_wait > avg_wait) { + est_wait = avg_wait; + best_stripe = index; + } + } + + return best_stripe; +} + static int find_live_mirror(struct btrfs_fs_info *fs_info, struct map_lookup *map, int first, int dev_replace_is_ongoing) @@ -5519,6 +5553,10 @@ static int find_live_mirror(struct btrfs_fs_info *fs_info, case BTRFS_READ_POLICY_PID: preferred_mirror = first + (current->pid % num_stripes); break; + case BTRFS_READ_POLICY_LATENCY: + preferred_mirror = btrfs_find_best_stripe(fs_info, map, first, + num_stripes); + break; } if (dev_replace_is_ongoing && diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h index 1997a4649a66..71ba1f0e93f4 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -222,6 +222,8 @@ enum btrfs_chunk_allocation_policy { enum btrfs_read_policy { /* Use process PID to choose the stripe */ BTRFS_READ_POLICY_PID, + /* Find and use device with the lowest latency */ + BTRFS_READ_POLICY_LATENCY, BTRFS_NR_READ_POLICY, };