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=-7.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_PASS,USER_AGENT_MUTT 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 0A693C10F0E for ; Mon, 15 Apr 2019 14:27:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CC7052075B for ; Mon, 15 Apr 2019 14:27:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726298AbfDOO1z (ORCPT ); Mon, 15 Apr 2019 10:27:55 -0400 Received: from mx2.suse.de ([195.135.220.15]:55690 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725789AbfDOO1z (ORCPT ); Mon, 15 Apr 2019 10:27:55 -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 922CEAD64 for ; Mon, 15 Apr 2019 14:27:54 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 304A9DA9C7; Mon, 15 Apr 2019 16:28:58 +0200 (CEST) Date: Mon, 15 Apr 2019 16:28:55 +0200 From: David Sterba To: Qu Wenruo Cc: linux-btrfs@vger.kernel.org Subject: Re: [PATCH v3 0/2] btrfs: trace: Trace events for btrfs tree locking Message-ID: <20190415142854.GH3476@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Qu Wenruo , linux-btrfs@vger.kernel.org References: <20190415131525.20274-1-wqu@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190415131525.20274-1-wqu@suse.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Mon, Apr 15, 2019 at 09:15:23PM +0800, Qu Wenruo wrote: > This branch can be fetched from github: > https://github.com/adam900710/linux/tree/trace_locking > Which is based on v5.1-rc4 tag. > > This patchset will introduce the following trace events for corresponding > functions: > btrfs_tree_lock (sleepable) > btrfs_tree_unlock > btrfs_tree_read_lock (sleepable) > btrfs_tree_read_unlock > btrfs_tree_read_unlock_blocking > btrfs_set_lock_blocking_read > btrfs_set_lock_blocking_write > btrfs_clear_lock_blocking_read > btrfs_clear_lock_blocking_write > btrfs_try_tree_read_lock > btrfs_try_tree_write_lock > btrfs_tree_read_lock_atomic > > The two sleepable ones will have extra info like start_ns, end_ns, > diff_ns. > Those two can be specially useful for tree lock wait time. > There is tool to utilize those two events already: > https://github.com/adam900710/btrfs-profiler/blob/master/tree_lock_wait.py > > The non-sleepable can be useful for possible user space based lock > leakage/dead lock detector. > > Changelog: > v2: > - Hide all ktime_get_ns() call out of trace events > So there will be no overhead if trace events are not enabled. > > v3: > - More output for human to take a glance > - More trace events for later bcc usage > Like lock leakage and deadlock detection. V3 looks good to me, thanks. The enhanced output of the sleepable lock is still sane.