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Fri, 19 Jul 2024 20:13:58 +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 QgiaJwbJmmZwSQAAD6G6ig (envelope-from ); Fri, 19 Jul 2024 20:13:58 +0000 Date: Fri, 19 Jul 2024 22:13:52 +0200 From: Petr Vorel To: Jens Axboe Cc: ltp@lists.linux.it, linux-block@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-xfs@vger.kernel.org, fstests@vger.kernel.org, Jan Kara , David Sterba , Filipe Manana , Amir Goldstein , Cyril Hrubis , Andrea Cervesato , Avinesh Kumar Subject: Re: [RFC] Slow down of LTP tests aiodio_sparse.c and dio_sparse.c in kernel 6.6 Message-ID: <20240719201352.GA782769@pevik> Reply-To: Petr Vorel References: <20240719174325.GA775414@pevik> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spamd-Result: default: False [0.49 / 50.00]; MID_RHS_NOT_FQDN(0.50)[]; HAS_REPLYTO(0.30)[pvorel@suse.cz]; R_DKIM_ALLOW(-0.20)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCPT_COUNT_TWELVE(0.00)[13]; MISSING_XM_UA(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_TLS_ALL(0.00)[]; DWL_DNSWL_BLOCKED(0.00)[suse.cz:dkim]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[lists.linux.it,vger.kernel.org,suse.cz,suse.com,gmail.com,suse.de]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.cz:dkim,suse.cz:replyto]; FROM_EQ_ENVFROM(0.00)[]; REPLYTO_EQ_FROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.cz:+] X-Spam-Level: X-Rspamd-Queue-Id: 0DCD41F7A5 X-Spam-Score: 0.49 X-Spam-Flag: NO X-Rspamd-Action: no action X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Spamd-Bar: / Hi Jens, all, > On 7/19/24 11:43 AM, Petr Vorel wrote: > > Hi all, > > LTP AIO DIO tests aiodio_sparse.c [1] and dio_sparse.c [2] (using [3]) slowed > > down on kernel 6.6 on Btrfs and XFS, when run with default parameters. These > > tests create 100 MB sparse file and write zeros (using libaio or O_DIRECT) while > > 16 other processes reads the buffer and check only zero is there. > > Runtime of this particular setup (i.e. 100 MB file) on Btrfs and XFS on the > > same system slowed down 9x (6.5: ~1 min 6.6: ~9 min). Ext4 is not affected. > > (Non default parameter creates much smaller file, thus the change is not that > > obvious). > > Because the slowdown has been here for few kernel releases I suppose nobody > > complained and the test is somehow artificial (nobody uses this in a real world). > > But still it'd be good to double check the problem. I can bisect a particular > > commit. > > Because 2 filesystems affected, could be "Improve asynchronous iomap DIO > > performance" [4] block layer change somehow related? > No, because that got disabled before release for unrelated reasons. Why > don't you just bisect it, since you have a simple test case? Jens, thanks for info. Sure, I'll bisect next week and report. The reason I reported before bisecting is because it wouldn't be the first time the test was "artificial" and therefore reported problem was not fixed. If it's a real problem I would expect it would be also caught by other people or even by fstests. Kind regards, Petr