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Thu, 4 Sep 2025 14:34:20 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id o2TeNGyjuWj6egAAD6G6ig (envelope-from ); Thu, 04 Sep 2025 14:34:20 +0000 Date: Thu, 4 Sep 2025 16:34:15 +0200 From: David Sterba To: Qu Wenruo Cc: kernel test robot , oe-lkp@lists.linux.dev, lkp@intel.com, linux-kernel@vger.kernel.org, David Sterba , linux-btrfs@vger.kernel.org Subject: Re: [linus:master] [btrfs] bddf57a707: stress-ng.sync-file.ops_per_sec 44.2% regression Message-ID: <20250904143415.GL5333@suse.cz> Reply-To: dsterba@suse.cz References: <202509031643.303d114c-lkp@intel.com> <9d6db7e9-318f-4242-9883-9eee8ee20f5e@suse.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <9d6db7e9-318f-4242-9883-9eee8ee20f5e@suse.com> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) X-Spam-Level: X-Spamd-Result: default: False [-4.00 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; HAS_REPLYTO(0.30)[dsterba@suse.cz]; NEURAL_HAM_SHORT(-0.20)[-0.998]; MIME_GOOD(-0.10)[text/plain]; RCPT_COUNT_SEVEN(0.00)[7]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_TLS_ALL(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; REPLYTO_ADDR_EQ_FROM(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.cz:replyto,suse.cz:mid,01.org:url]; RCVD_COUNT_TWO(0.00)[2]; REPLYTO_DOM_NEQ_TO_DOM(0.00)[] X-Spam-Flag: NO X-Spam-Score: -4.00 On Wed, Sep 03, 2025 at 06:18:01PM +0930, Qu Wenruo wrote: > 在 2025/9/3 18:14, kernel test robot 写道: > > > > Hello, > > > > kernel test robot noticed a 44.2% regression of stress-ng.sync-file.ops_per_sec on: > > > > > > commit: bddf57a70781ef8821d415200bdbcb71f443993a ("btrfs: delay btrfs_open_devices() until super block is created") > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master > > > > [still regression on linus/master fb679c832b6497f19fffb8274c419783909c0912] > > [still regression on linux-next/master 3cace99d63192a7250461b058279a42d91075d0c] > > > > testcase: stress-ng > > config: x86_64-rhel-9.4 > > compiler: gcc-12 > > test machine: 64 threads 2 sockets Intel(R) Xeon(R) Gold 6346 CPU @ 3.10GHz (Ice Lake) with 256G memory > > parameters: > > > > nr_threads: 100% > > disk: 1HDD > > testtime: 60s > > fs: btrfs > > test: sync-file > > cpufreq_governor: performance > > > > > > > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > > the same patch/commit), kindly add following tags > > | Reported-by: kernel test robot > > | Closes: https://lore.kernel.org/oe-lkp/202509031643.303d114c-lkp@intel.com > > > > > > Details are as below: > > --------------------------------------------------------------------------------------------------> > > > > > > The kernel config and materials to reproduce are available at: > > https://download.01.org/0day-ci/archive/20250903/202509031643.303d114c-lkp@intel.com > > > > ========================================================================================= > > compiler/cpufreq_governor/disk/fs/kconfig/nr_threads/rootfs/tbox_group/test/testcase/testtime: > > gcc-12/performance/1HDD/btrfs/x86_64-rhel-9.4/100%/debian-12-x86_64-20240206.cgz/lkp-icl-2sp8/sync-file/stress-ng/60s > > > > commit: > > de339cbfb4 ("btrfs: call bdev_fput() to reclaim the blk_holder immediately") > > bddf57a707 ("btrfs: delay btrfs_open_devices() until super block is created") > > This doesn't sound sane to me. > > The two commits are only affecting btrfs mounting/unmounting, I can not > make any sense on why they would affect performance. > > Or does stress-ng doing a lot of mounting/unmounting? Yeah, unless there's some indirect way how mount affects the tests the numbers do not match the identified patches. The difference is roughly consistent in all the stats to be about 40% less so it's like it's doing half of the work. Delayed device opening does not explain that.