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=-8.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_PASS,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 5F67DC43381 for ; Thu, 28 Feb 2019 10:03:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 37BBC2183F for ; Thu, 28 Feb 2019 10:03:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732245AbfB1KDB (ORCPT ); Thu, 28 Feb 2019 05:03:01 -0500 Received: from mx2.suse.de ([195.135.220.15]:59282 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1731561AbfB1KDA (ORCPT ); Thu, 28 Feb 2019 05:03:00 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id C11FDADD1 for ; Thu, 28 Feb 2019 10:02:59 +0000 (UTC) From: Qu Wenruo To: linux-btrfs@vger.kernel.org Subject: [PATCH 0/2] btrfs: trace: Add trace events for extent_io_tree Date: Thu, 28 Feb 2019 18:02:53 +0800 Message-Id: <20190228100255.10953-1-wqu@suse.com> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org This patchset can be fetched from github: https://github.com/adam900710/linux/tree/ftrace_extent_io_tree Which is based on v5.0-rc7 tag. Btrfs uses (almost abuse) extent_io_tree for a lot of operations, e.g: - Tree block locking BTRFS_I(btree_inode)->io_tree - Page status tracing BTRFS_I(file_inode)->io_tree and BTRFS_I(file_inode)->io_failure_tree transaction->dirty_pages - Pinned down extents tracing fs_info->freed_extents[2] ... However we don't have any trace events for us to understand how btrfs works. This patchset will introduce trace events for set/clear/convert_extent_bit(). The output examples and extra notes are: (copied from the 2nd patch) btrfs_set_extent_bit: io_tree=INODE_IO_TREE ino=1 root=1 start=22036480 len=4096 set_bits=LOCKED btrfs_set_extent_bit: io_tree=INODE_IO_TREE ino=1 root=1 start=22040576 len=4096 set_bits=LOCKED btrfs_set_extent_bit: io_tree=INODE_IO_TREE ino=1 root=1 start=22044672 len=4096 set_bits=LOCKED btrfs_set_extent_bit: io_tree=INODE_IO_TREE ino=1 root=1 start=22048768 len=4096 set_bits=LOCKED btrfs_clear_extent_bit: io_tree=INODE_IO_TREE ino=1 root=1 start=22036480 len=16384 clear_bits=LOCKED ^^^ Extent buffer 22036480 read from disc, the locking progress btrfs_set_extent_bit: io_tree=TRANS_DIRTY_PAGES ino=1 root=1 start=30425088 len=16384 set_bits=DIRTY btrfs_set_extent_bit: io_tree=TRANS_DIRTY_PAGES ino=1 root=1 start=30441472 len=16384 set_bits=DIRTY ^^^ 2 new tree blocks allocated in one transaction btrfs_set_extent_bit: io_tree=FREED_EXTENTS0 ino=0 root=0 start=30523392 len=16384 set_bits=DIRTY btrfs_set_extent_bit: io_tree=FREED_EXTENTS0 ino=0 root=0 start=30556160 len=16384 set_bits=DIRTY ^^^ 2 old tree blocks get pinned down There are 2 points which need extra attention: 1) Those trace events are pretty heavy The following workload would generate over 400 trace events. mkfs.btrfs -f $dev start_trace mount $dev $mnt -o enospc_debug sync touch $mnt/file1 touch $mnt/file2 touch $mnt/file3 xfs_io -f -c "pwrite 0 16k" $mnt/file4 umount $mnt end_trace It's not recommended to use them in real world environment. 2) No way to distinguish between different btrfs filesystems Due to the fact that we can't get fs_info easily from extent_io_tree, there is no way to distinguish events from different fses. To avoid extra noise, please ensure there is only one btrfs in your test environment. Qu Wenruo (2): btrfs: Introduce extent_io_tree::owner to distinguish different io_trees btrfs: trace: Add trace events for extent_io_tree fs/btrfs/disk-io.c | 12 ++- fs/btrfs/extent_io.c | 7 +- fs/btrfs/extent_io.h | 20 +++- fs/btrfs/inode.c | 5 +- fs/btrfs/relocation.c | 3 +- fs/btrfs/tests/btrfs-tests.c | 6 +- fs/btrfs/tests/extent-io-tests.c | 2 +- fs/btrfs/transaction.c | 2 +- include/trace/events/btrfs.h | 151 +++++++++++++++++++++++++++++++ 9 files changed, 194 insertions(+), 14 deletions(-) -- 2.21.0