From patchwork Fri Jan 22 20:47:42 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Omar Sandoval X-Patchwork-Id: 12040521 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=-11.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,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 354D5C433DB for ; Fri, 22 Jan 2021 20:54:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0381023B08 for ; Fri, 22 Jan 2021 20:54:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728700AbhAVUyO (ORCPT ); Fri, 22 Jan 2021 15:54:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49756 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730888AbhAVUwQ (ORCPT ); Fri, 22 Jan 2021 15:52:16 -0500 Received: from mail-pf1-x434.google.com (mail-pf1-x434.google.com [IPv6:2607:f8b0:4864:20::434]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C6F31C0698C2 for ; Fri, 22 Jan 2021 12:48:16 -0800 (PST) Received: by mail-pf1-x434.google.com with SMTP id w18so4616055pfu.9 for ; Fri, 22 Jan 2021 12:48:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=osandov-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=aLz7NJZ43LYbj/J4fx7gdxsDjTPNW6ZMYhnwdB8KJhA=; b=mQ1crHnp8Y/EDtPjsk1JcYW+khWf/np1bYK0Ovfk6EAoNtAK9Q5oi1qKArmAps05ji I5AjJZPSQmrvepU3BamH2o40Zh7pkMLEzk8ClS8ca7q6ElimQ5LHmNFsQFwkhbtzZPiX PpBgX8iirJxPI1H5Ht0YV9E+HbG7dwTqCC5mt0klj/++epC0zZK81Q6ssiODa6tY2efv mKA9XNo2bS4mjGua/9u+qapnVedm1QPey515tub4IJMrQu4AUTwymZsHTD/+7kHb1JhG xrX29rGpPtwrLkD6OQvZHZAcz1ltstIyTZuI/NcsBPSFp6afJWdhCZ8GTGCfObiezREn SHOw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=aLz7NJZ43LYbj/J4fx7gdxsDjTPNW6ZMYhnwdB8KJhA=; b=nbsXZrSuP0bJmKcjpNmC1/O8kKz4Ndd7K5plpMqkDiv73VYZaCeUtmgI6Ry3SF3ve2 W+YphTsDWPH7sptYOTBbnIgk39V3IX9wy6WUgqKo17MtEx01QvU5oQBiuJjSTGbK3fGp N2zdHvuKgExiYYOFDPEoXWZ6n7Q9dQpriZw7kxzY0eHPqHo3DhKCWUNK+kNxnO9T2cY+ w0eBRW8Y4pNO3it9rJuGABZiAQvPZdlfjfYS3YeEqA3eXp71j6cq0gy0LI/vXbJ5zaJL ma+HKVVAPUXqnv0HW4BDRhysDHTHYTgOeolvVDaOdW38J/FI5zyh/6Wazsd9TcXIW+bU bvVQ== X-Gm-Message-State: AOAM533TYdqmaJEjP5SBA6Xgvqsz/SkrE/Nz1mWqUQh5b/yM7D6aDx8g deIh4ciNvY045E+4nSCYeyrRX19DISg8XA== X-Google-Smtp-Source: ABdhPJyAMhc/McZExSwA51fKTM23Iumtj6GgZHs1aBcvqEzYx155mEkgEzViZ6p+nB/24N1zfM1faQ== X-Received: by 2002:a63:804a:: with SMTP id j71mr6326472pgd.307.1611348495638; Fri, 22 Jan 2021 12:48:15 -0800 (PST) Received: from relinquished.tfbnw.net ([2620:10d:c090:400::5:ea88]) by smtp.gmail.com with ESMTPSA id y16sm9865617pfb.83.2021.01.22.12.48.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 Jan 2021 12:48:14 -0800 (PST) From: Omar Sandoval To: linux-btrfs@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, kernel-team@fb.com Subject: [PATCH v3 0/5] btrfs: implement send/receive of compressed extents without decompressing Date: Fri, 22 Jan 2021 12:47:42 -0800 Message-Id: X-Mailer: git-send-email 2.30.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: Omar Sandoval This series uses the interface added in "fs: interface for directly reading/writing compressed data" to send and receive compressed data without wastefully decompressing and recompressing it. It does so by 1. Bumping the send stream protocol version to 2. 2. Adding a new command, BTRFS_SEND_C_ENCODED_WRITE, and its associated attributes that indicates a write using the new encoded I/O interface. 3. Sending compressed extents with BTRFS_SEND_C_ENCODED_WRITE when requested by the user. 4. Falling back to decompressing and writing the decompressed data if encoded I/O fails. Benchmarks ========== I ran some benchmarks on send and receive of a zstd (level 3) compressed snapshot of a server's root filesystem which is about 23GB when compressed and 50GB when decompressed. Send v1: 0.41user 81.97system 2:21.71elapsed 58%CPU (0avgtext+0avgdata 2900maxresident)k 47182656inputs+0outputs (10major+119minor)pagefaults 0swaps Send compressed: 0.43user 60.53system 2:20.62elapsed 43%CPU (0avgtext+0avgdata 2836maxresident)k 47778864inputs+0outputs (8major+117minor)pagefaults 0swaps In this case, the bottleneck for send is reading the metadata trees and data from disk, so there's not much of a wall time improvement, but since the kernel doesn't have to decompress the data in the compressed case, it uses significantly less CPU and system time. Receive v1 into a filesystem with compress=none: 15.58user 62.36system 7:34.44elapsed 17%CPU (0avgtext+0avgdata 3028maxresident)k 104719648inputs+105333248outputs (1major+140minor)pagefaults 0swaps Receive v1 into a filesystem with compress-force=zstd: 15.45user 63.99system 5:11.57elapsed 25%CPU (0avgtext+0avgdata 3100maxresident)k 104587240inputs+105379328outputs (1major+143minor)pagefaults 0swaps Receive compressed into a filesystem with compress-force=zstd: 7.95user 44.53system 3:42.79elapsed 23%CPU (0avgtext+0avgdata 2992maxresident)k 46909600inputs+21603216outputs (2major+176minor)pagefaults 0swaps Without compressed receive, recompressing the data is still a wall time win because it requires much less I/O. However, compressed receive reduces the wall time even further. The v1 send stream is 50GB, and the v2 send stream is 23 GB. The v1 send stream compresses down to 17GB with zstd (level 3), so compressed send gets pretty close with no extra CPU overhead (the reason that compressed send is still larger is of course that we compress extents individually, which does not compress as efficiently as compressing the entire filesystem representation in one go). # ls -lh v1.send v1.send.zst compressed.send -rw-r--r-- 1 root root 23G Aug 17 12:34 compressed.send -rw-r--r-- 1 root root 50G Aug 17 12:13 v1.send -rw-r--r-- 1 root root 17G Aug 17 12:28 v1.send.zst Protocol Updates ================ This series makes some changes to the send stream protocol beyond adding the encoded write command/attributes and bumping the version. Namely, v1 has a 64k limit on the size of a write due to the 16-bit attribute length. This is not enough for encoded writes, as compressed extents may be up to 128k and cannot be split up. To address this, the BTRFS_SEND_A_DATA is treated specially in v2: its length is implicitly the remaining length of the command (which has a 32-bit length). This was the least bad of the options I considered. There are other commands that we've been wanting to add to the protocol: fallocate and FS_IOC_SETFLAGS. This series reserves their command and attribute numbers but does not implement kernel support for emitting them. However, it does implement support in receive for them, so the kernel can start emitting those whenever we get around to implementing them. Interface ========= For the send ioctl, stream version 2 is opt-in, and compressed writes are opt-in separately (but dependent on) stream version 2. Accordingly, `btrfs send` now accepts a `--stream-version` option and a `--compressed-data` option; the latter implies `--stream-version 2`. `btrfs receive` also accepts a `--force-decompress` option that forces the fallback to decompressing and writing the decompressed data. These options are provided to give the user flexibility in case they don't want their receiving filesytem to be compressed. Patches ======= The kernel patches are based on kdave/misc-next plus v7 of my "fs: interface for directly reading/writing compressed data" series. Patches 1-3 do some preparation for stream v2 and compressed send. Patch 4 implements compressed send. Patch 5 modifies the ioctl to accept the new flags and enable the new feature. Changes since v2 [1]: - Added reviewed-bys. Omar Sandoval (5): btrfs: add send stream v2 definitions btrfs: send: write larger chunks when using stream v2 btrfs: send: allocate send buffer with alloc_page() and vmap() for v2 btrfs: send: send compressed extents with encoded writes btrfs: send: enable support for stream v2 and compressed writes fs/btrfs/ctree.h | 4 + fs/btrfs/inode.c | 6 +- fs/btrfs/send.c | 307 +++++++++++++++++++++++++++++++++---- fs/btrfs/send.h | 32 +++- include/uapi/linux/btrfs.h | 17 +- 5 files changed, 332 insertions(+), 34 deletions(-) The btrfs-progs patches were written by Boris Burkov with some updates from me. Patches 1-5 are preparation. Patch 6 implements encoded writes. Patch 7 implements the fallback to decompressing. Patches 9 and 10 implement the other commands. Patch 10 adds the new `btrfs send` options. Patch 11 adds a test case. Changes since v2 [1]: - Dropped O_CLOEXEC addition now that the requirement was dropped in the kernel. - Updated encoded I/O definitions to match the new ones in the kernel. Boris Burkov (11): btrfs-progs: receive: support v2 send stream larger tlv_len btrfs-progs: receive: dynamically allocate sctx->read_buf btrfs-progs: receive: support v2 send stream DATA tlv format btrfs-progs: receive: add send stream v2 cmds and attrs to send.h btrfs-progs: receive: add stub implementation for pwritev2 btrfs-progs: receive: process encoded_write commands btrfs-progs: receive: encoded_write fallback to explicit decode and write btrfs-progs: receive: process fallocate commands btrfs-progs: receive: process setflags ioctl commands btrfs-progs: send: stream v2 ioctl flags btrfs-progs: receive: add tests for basic encoded_write send/receive Documentation/btrfs-receive.asciidoc | 4 + Documentation/btrfs-send.asciidoc | 16 +- Makefile | 4 +- cmds/receive-dump.c | 31 +- cmds/receive.c | 403 +++++++++++++++++- cmds/send.c | 54 ++- common/send-stream.c | 157 +++++-- common/send-stream.h | 7 + configure.ac | 1 + ioctl.h | 17 +- libbtrfsutil/btrfs.h | 17 +- send.h | 19 +- stubs.c | 24 ++ stubs.h | 57 +++ .../043-receive-write-encoded/test.sh | 114 +++++ 15 files changed, 874 insertions(+), 51 deletions(-) create mode 100644 stubs.c create mode 100644 stubs.h create mode 100755 tests/misc-tests/043-receive-write-encoded/test.sh 1: https://lore.kernel.org/linux-btrfs/cover.1605723600.git.osandov@fb.com/