From patchwork Tue Apr 2 09:45:54 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qu Wenruo X-Patchwork-Id: 10881305 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 89C10922 for ; Tue, 2 Apr 2019 09:46:01 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 72E1B28640 for ; Tue, 2 Apr 2019 09:46:01 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 63CA828785; Tue, 2 Apr 2019 09:46:01 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C9C4528640 for ; Tue, 2 Apr 2019 09:46:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727082AbfDBJp7 (ORCPT ); Tue, 2 Apr 2019 05:45:59 -0400 Received: from mx2.suse.de ([195.135.220.15]:53522 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726157AbfDBJp7 (ORCPT ); Tue, 2 Apr 2019 05:45:59 -0400 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 55113ACBF for ; Tue, 2 Apr 2019 09:45:57 +0000 (UTC) From: Qu Wenruo To: linux-btrfs@vger.kernel.org Subject: [PATCH v2] btrfs: trace: Introduce trace events for sleepable tree lock Date: Tue, 2 Apr 2019 17:45:54 +0800 Message-Id: <20190402094554.8353-1-wqu@suse.com> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP There are two tree lock events which can sleep: - btrfs_tree_read_lock() - btrfs_tree_lock() Sometimes we may need to look into the concurrency picture of the fs. For that case, we need the execution time of above two functions and the owner of @eb. Here we introduce a trace events for user space tools like bcc, to get the execution time of above two functions, and get detailed owner info where eBPF code can't. All the overhead is hidden behind the trace events, so if events are not enabled, there is no overhead. Also, since this patch and later user space tool only cares about the execution time and owner, other info like bytenr is ignored in this events. Signed-off-by: Qu Wenruo --- Changelog: v2: - Hide all ktime_get_ns() call behind trace events So there will be no overhead if trace events are not enabled. --- fs/btrfs/locking.c | 12 ++++++++++++ include/trace/events/btrfs.h | 36 ++++++++++++++++++++++++++++++++++++ 2 files changed, 48 insertions(+) diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c index 6df03ba36026..67b77f1d113e 100644 --- a/fs/btrfs/locking.c +++ b/fs/btrfs/locking.c @@ -158,6 +158,10 @@ void btrfs_clear_lock_blocking_write(struct extent_buffer *eb) */ void btrfs_tree_read_lock(struct extent_buffer *eb) { + u64 start_ns = 0; + + if (trace_btrfs_tree_read_lock_enabled()) + start_ns = ktime_get_ns(); again: BUG_ON(!atomic_read(&eb->blocking_writers) && current->pid == eb->lock_owner); @@ -174,6 +178,7 @@ void btrfs_tree_read_lock(struct extent_buffer *eb) BUG_ON(eb->lock_nested); eb->lock_nested = true; read_unlock(&eb->lock); + trace_btrfs_tree_read_lock(eb, start_ns); return; } if (atomic_read(&eb->blocking_writers)) { @@ -184,6 +189,7 @@ void btrfs_tree_read_lock(struct extent_buffer *eb) } btrfs_assert_tree_read_locks_get(eb); btrfs_assert_spinning_readers_get(eb); + trace_btrfs_tree_read_lock(eb, start_ns); } /* @@ -299,6 +305,11 @@ void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb) */ void btrfs_tree_lock(struct extent_buffer *eb) { + u64 start_ns = 0; + + if (trace_btrfs_tree_lock_enabled()) + start_ns = ktime_get_ns(); + WARN_ON(eb->lock_owner == current->pid); again: wait_event(eb->read_lock_wq, atomic_read(&eb->blocking_readers) == 0); @@ -312,6 +323,7 @@ void btrfs_tree_lock(struct extent_buffer *eb) btrfs_assert_spinning_writers_get(eb); btrfs_assert_tree_write_locks_get(eb); eb->lock_owner = current->pid; + trace_btrfs_tree_lock(eb, start_ns); } /* diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h index 8b12753fee78..406a71571254 100644 --- a/include/trace/events/btrfs.h +++ b/include/trace/events/btrfs.h @@ -2005,6 +2005,42 @@ TRACE_EVENT(btrfs_convert_extent_bit, __print_flags(__entry->clear_bits, "|", EXTENT_FLAGS)) ); +DECLARE_EVENT_CLASS(btrfs_sleep_tree_lock, + TP_PROTO(const struct extent_buffer *eb, u64 start_ns), + + TP_ARGS(eb, start_ns), + + TP_STRUCT__entry_btrfs( + __field( u64, start_ns ) + __field( u64, end_ns ) + __field( u64, owner ) + __field( int, is_log_tree ) + ), + + TP_fast_assign_btrfs(eb->fs_info, + __entry->start_ns = start_ns; + __entry->end_ns = ktime_get_ns(); + __entry->owner = btrfs_header_owner(eb); + __entry->is_log_tree = (eb->log_index >= 0); + ), + + TP_printk_btrfs("start_ns=%llu end_ns=%llu owner=%llu is_log_tree=%d", + __entry->start_ns, __entry->end_ns, __entry->owner, + __entry->is_log_tree) +); + +DEFINE_EVENT(btrfs_sleep_tree_lock, btrfs_tree_read_lock, + TP_PROTO(const struct extent_buffer *eb, u64 start_ns), + + TP_ARGS(eb, start_ns) +); + +DEFINE_EVENT(btrfs_sleep_tree_lock, btrfs_tree_lock, + TP_PROTO(const struct extent_buffer *eb, u64 start_ns), + + TP_ARGS(eb, start_ns) +); + #endif /* _TRACE_BTRFS_H */ /* This part must be outside protection */