From patchwork Sun Oct 24 15:31:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Goffredo Baroncelli X-Patchwork-Id: 12580287 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5C613C433F5 for ; Sun, 24 Oct 2021 15:39:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3335A60EBC for ; Sun, 24 Oct 2021 15:39:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231172AbhJXPl5 (ORCPT ); Sun, 24 Oct 2021 11:41:57 -0400 Received: from michael.mail.tiscali.it ([213.205.33.246]:57658 "EHLO smtp.tiscali.it" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S229788AbhJXPl5 (ORCPT ); Sun, 24 Oct 2021 11:41:57 -0400 Received: from venice.bhome ([78.14.151.87]) by michael.mail.tiscali.it with id 9rXD2600J1tPKGW01rXDap; Sun, 24 Oct 2021 15:31:14 +0000 x-auth-user: kreijack@tiscali.it From: Goffredo Baroncelli To: linux-btrfs@vger.kernel.org Cc: Zygo Blaxell , Josef Bacik , David Sterba , Sinnamohideen Shafeeq , Goffredo Baroncelli Subject: [RFC][V8][PATCH 0/5] btrfs: allocation_hint mode Date: Sun, 24 Oct 2021 17:31:03 +0200 Message-Id: X-Mailer: git-send-email 2.33.0 Reply-To: Goffredo Baroncelli MIME-Version: 1.0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tiscali.it; s=smtp; t=1635089474; bh=y74YL61PgHUa/D6N1GLVMmfVNziNRsvEsnBXWGp72a0=; h=From:To:Cc:Subject:Date:Reply-To; b=GselEjhoSyYPtXGPJGDRhM4ppvihPi5jsHHxe9wotTWfgEEPMYhObJZmgshuCvqTh lq8sFaxQGccjKQ747y4Q5Me2yxi5QW2jwIsv+3MGflcDCdbAoZc6GY3jKOmRUvS2cZ /9Icq3LTat7cNlmmZbp1rkh6S8jxA5ScRU8sO8pk= Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: Goffredo Baroncelli Hi all, This patches set was born after some discussion between me, Zygo and Josef. Some details can be found in https://github.com/btrfs/btrfs-todo/issues/19. Some further information about a real use case can be found in https://lore.kernel.org/linux-btrfs/20210116002533.GE31381@hungrycats.org/ Reently Shafeeq told me that he is interested too, due to the performance gain. In this revision I switched away from an ioctl API in favor of a sysfs API ( see patch #2 and #3). The idea behind this patches set, is to dedicate some disks (the fastest one) to the metadata chunk. My initial idea was a "soft" hint. However Zygo asked an option for a "strong" hint (== mandatory). The result is that each disk can be "tagged" by one of the following flags: - BTRFS_DEV_ALLOCATION_METADATA_ONLY - BTRFS_DEV_ALLOCATION_PREFERRED_METADATA - BTRFS_DEV_ALLOCATION_PREFERRED_DATA - BTRFS_DEV_ALLOCATION_DATA_ONLY When the chunk allocator search a disks to allocate a chunk, scans the disks in an order decided by these tags. For metadata, the order is: *_METADATA_ONLY *_PREFERRED_METADATA *_PREFERRED_DATA The *_DATA_ONLY are not eligible from metadata chunk allocation. For the data chunk, the order is reversed, and the *_METADATA_ONLY are excluded. The exact sort logic is to sort first for the "tag", and then for the space available. If there is no space available, the next "tag" disks set are selected. To set these tags, a new property called "allocation_hint" was created. There is a dedicated btrfs-prog patches set [[PATCH V5] btrfs-progs: allocation_hint disk property]. $ sudo mount /dev/loop0 /mnt/test-btrfs/ $ for i in /dev/loop[0-9]; do sudo ./btrfs prop get $i allocation_hint; done devid=1, path=/dev/loop0: allocation_hint=PREFERRED_METADATA devid=2, path=/dev/loop1: allocation_hint=PREFERRED_METADATA devid=3, path=/dev/loop2: allocation_hint=PREFERRED_DATA devid=4, path=/dev/loop3: allocation_hint=PREFERRED_DATA devid=5, path=/dev/loop4: allocation_hint=PREFERRED_DATA devid=6, path=/dev/loop5: allocation_hint=DATA_ONLY devid=7, path=/dev/loop6: allocation_hint=METADATA_ONLY devid=8, path=/dev/loop7: allocation_hint=METADATA_ONLY $ sudo ./btrfs fi us /mnt/test-btrfs/ Overall: Device size: 2.75GiB Device allocated: 1.34GiB Device unallocated: 1.41GiB Device missing: 0.00B Used: 400.89MiB Free (estimated): 1.04GiB (min: 1.04GiB) Data ratio: 2.00 Metadata ratio: 1.00 Global reserve: 3.25MiB (used: 0.00B) Multiple profiles: no Data,RAID1: Size:542.00MiB, Used:200.25MiB (36.95%) /dev/loop0 288.00MiB /dev/loop1 288.00MiB /dev/loop2 127.00MiB /dev/loop3 127.00MiB /dev/loop4 127.00MiB /dev/loop5 127.00MiB Metadata,single: Size:256.00MiB, Used:384.00KiB (0.15%) /dev/loop1 256.00MiB System,single: Size:32.00MiB, Used:16.00KiB (0.05%) /dev/loop0 32.00MiB Unallocated: /dev/loop0 704.00MiB /dev/loop1 480.00MiB /dev/loop2 1.00MiB /dev/loop3 1.00MiB /dev/loop4 1.00MiB /dev/loop5 1.00MiB /dev/loop6 128.00MiB /dev/loop7 128.00MiB # change the tag of some disks $ sudo ./btrfs prop set /dev/loop0 allocation_hint DATA_ONLY $ sudo ./btrfs prop set /dev/loop1 allocation_hint DATA_ONLY $ sudo ./btrfs prop set /dev/loop5 allocation_hint METADATA_ONLY $ for i in /dev/loop[0-9]; do sudo ./btrfs prop get $i allocation_hint; done devid=1, path=/dev/loop0: allocation_hint=DATA_ONLY devid=2, path=/dev/loop1: allocation_hint=DATA_ONLY devid=3, path=/dev/loop2: allocation_hint=PREFERRED_DATA devid=4, path=/dev/loop3: allocation_hint=PREFERRED_DATA devid=5, path=/dev/loop4: allocation_hint=PREFERRED_DATA devid=6, path=/dev/loop5: allocation_hint=METADATA_ONLY devid=7, path=/dev/loop6: allocation_hint=METADATA_ONLY devid=8, path=/dev/loop7: allocation_hint=METADATA_ONLY $ sudo btrfs bal start --full-balance /mnt/test-btrfs/ $ sudo ./btrfs fi us /mnt/test-btrfs/ Overall: Device size: 2.75GiB Device allocated: 735.00MiB Device unallocated: 2.03GiB Device missing: 0.00B Used: 400.72MiB Free (estimated): 1.10GiB (min: 1.10GiB) Data ratio: 2.00 Metadata ratio: 1.00 Global reserve: 3.25MiB (used: 0.00B) Multiple profiles: no Data,RAID1: Size:288.00MiB, Used:200.19MiB (69.51%) /dev/loop0 288.00MiB /dev/loop1 288.00MiB Metadata,single: Size:127.00MiB, Used:336.00KiB (0.26%) /dev/loop5 127.00MiB System,single: Size:32.00MiB, Used:16.00KiB (0.05%) /dev/loop7 32.00MiB Unallocated: /dev/loop0 736.00MiB /dev/loop1 736.00MiB /dev/loop2 128.00MiB /dev/loop3 128.00MiB /dev/loop4 128.00MiB /dev/loop5 1.00MiB /dev/loop6 128.00MiB /dev/loop7 96.00MiB #As you can see all the metadata were placed on the disk loop5/loop7 even if #the most empty one are loop0 and loop1. TODO: - more tests - the tool which show the space available should consider the tagging (eg the disks tagged by _METADATA_ONLY should be excluded from the data availability) Comments are welcome BR G.Baroncelli