From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9DBFB15D0 for ; Fri, 8 Mar 2024 17:01:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709917272; cv=none; b=Qtw8Qwk220M5mjKnV9SFzv6xiZCjgBeds2zcDrhYQoS/ieifSkT8FBrfEXteG3kUWzeaS5/mHyo3ScjWyTE283Uxcss2E3Xd4mC3Ivu4H9PV3d3LCZqxSmK54Ntg9zvxjDFcFG6al5GWoaJbXwCWlxnysrWO0+T64TjN/ff/iBw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709917272; c=relaxed/simple; bh=i7E5PxhRRLf8NAgevQH7wCn8vUIulfXQVlSFAq2zhOk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ERyjRC6130a1pop/2ELcQlxvmQOEBUP6hExMo18qvB8fPyFE6UIJrEyDhfrImJ2g1mjTsWBD8NUxogOuPP7pM/kcHA95+5hRVg21HKJqWEY8RIy7n+Eu7T0OhC/hrRxTw/I1bBPuTg2ePoxyUpjF7g+qEgKlsL83wjf1yNVRVdk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz; spf=pass smtp.mailfrom=suse.cz; dkim=pass (1024-bit key) header.d=suse.cz header.i=@suse.cz header.b=qygk1F0i; dkim=permerror (0-bit key) header.d=suse.cz header.i=@suse.cz header.b=eTPAwJo4; dkim=pass (1024-bit key) header.d=suse.cz header.i=@suse.cz header.b=qygk1F0i; dkim=permerror (0-bit key) header.d=suse.cz header.i=@suse.cz header.b=eTPAwJo4; arc=none smtp.client-ip=195.135.223.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.cz Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=suse.cz header.i=@suse.cz header.b="qygk1F0i"; dkim=permerror (0-bit key) header.d=suse.cz header.i=@suse.cz header.b="eTPAwJo4"; dkim=pass (1024-bit key) header.d=suse.cz header.i=@suse.cz header.b="qygk1F0i"; dkim=permerror (0-bit key) header.d=suse.cz header.i=@suse.cz header.b="eTPAwJo4" Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 6EA0B67152; Fri, 8 Mar 2024 16:00:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1709913659; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=L6hUun/q+Fap0ufLg3Iy252uXcivOwOteBZoVbnftMc=; b=qygk1F0ikhZV+Q5FmhkAY2wVtQq6qbf5neNldYMDzyuZpjw1EhvQn15XahcLCuayk5HPvU nMWEuNZYmzVd9SJmiHxqnuNtvUaOxoNd9HwP5DG/sA6NxRUWWRQN68ip2yi3YkdaMKYlC0 uJTz8eGlxcH7Ba7Oi8an0OG6vaN0vX8= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1709913659; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=L6hUun/q+Fap0ufLg3Iy252uXcivOwOteBZoVbnftMc=; b=eTPAwJo4cO522F7GeOHztZW7KMGWjbETS3JzjWjWfii1Mz+tKTu+V9EprV8jVW9rY3ltVz UakuUoeHVgGv6JCg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1709913659; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=L6hUun/q+Fap0ufLg3Iy252uXcivOwOteBZoVbnftMc=; b=qygk1F0ikhZV+Q5FmhkAY2wVtQq6qbf5neNldYMDzyuZpjw1EhvQn15XahcLCuayk5HPvU nMWEuNZYmzVd9SJmiHxqnuNtvUaOxoNd9HwP5DG/sA6NxRUWWRQN68ip2yi3YkdaMKYlC0 uJTz8eGlxcH7Ba7Oi8an0OG6vaN0vX8= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1709913659; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=L6hUun/q+Fap0ufLg3Iy252uXcivOwOteBZoVbnftMc=; b=eTPAwJo4cO522F7GeOHztZW7KMGWjbETS3JzjWjWfii1Mz+tKTu+V9EprV8jVW9rY3ltVz UakuUoeHVgGv6JCg== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 5F78413310; Fri, 8 Mar 2024 16:00:59 +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 np9HFzs262VgTgAAD6G6ig (envelope-from ); Fri, 08 Mar 2024 16:00:59 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id E6788A0803; Fri, 8 Mar 2024 17:00:58 +0100 (CET) Date: Fri, 8 Mar 2024 17:00:58 +0100 From: Jan Kara To: Amir Goldstein Cc: Jan Kara , Jens Axboe , Christian Brauner , linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v3] fsnotify: optimize the case of no parent watcher Message-ID: <20240308160058.eu7thhohy2d3xtcz@quack3> References: <20240116113247.758848-1-amir73il@gmail.com> <20240116120434.gsdg7lhb4pkcppfk@quack3> <20240124160758.zodsoxuzfjoancly@quack3> <20240214112310.ovg2w3p6wztuslnw@quack3> <20240215083648.dhjgdj43npgkoe7p@quack3> Precedence: bulk X-Mailing-List: linux-fsdevel@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: X-Spam-Level: Authentication-Results: smtp-out2.suse.de; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=qygk1F0i; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=eTPAwJo4 X-Spamd-Result: default: False [-2.81 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; R_DKIM_ALLOW(-0.20)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; URIBL_BLOCKED(0.00)[suse.com:email,suse.cz:email,suse.cz:dkim]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_GOOD(-0.10)[text/plain]; RCPT_COUNT_FIVE(0.00)[5]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.cz:+]; MX_GOOD(-0.01)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:email,suse.cz:email,suse.cz:dkim]; FREEMAIL_TO(0.00)[gmail.com]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; MID_RHS_NOT_FQDN(0.50)[]; RCVD_TLS_ALL(0.00)[]; BAYES_HAM(-3.00)[100.00%]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from] X-Spam-Score: -2.81 X-Rspamd-Queue-Id: 6EA0B67152 X-Spam-Flag: NO X-Rspamd-Server: rspamd1.dmz-prg2.suse.org On Wed 06-03-24 16:51:06, Amir Goldstein wrote: > On Thu, Feb 15, 2024 at 10:36 AM Jan Kara wrote: > > On Wed 14-02-24 15:40:31, Amir Goldstein wrote: > > > > > > > Merged your improvement now (and I've split off the cleanup into a separate > > > > > > > change and dropped the creation of fsnotify_path() which seemed a bit > > > > > > > pointless with a single caller). All pushed out. > > > > > > > > > > > > > > > > > > > > > > > Jan & Jens, > > > > > > > > > > Although Jan has already queued this v3 patch with sufficient performance > > > > > improvement for Jens' workloads, I got a performance regression report from > > > > > kernel robot on will-it-scale microbenchmark (buffered write loop) > > > > > on my fan_pre_content patches, so I tried to improve on the existing solution. > > > > > > > > > > I tried something similar to v1/v2 patches, where the sb keeps accounting > > > > > of the number of watchers for specific sub-classes of events. > > > > > > > > > > I've made two major changes: > > > > > 1. moved to counters into a per-sb state object fsnotify_sb_connector > > > > > as Christian requested > > > > > 2. The counters are by fanotify classes, not by specific events, so they > > > > > can be used to answer the questions: > > > > > a) Are there any fsnotify watchers on this sb? > > > > > b) Are there any fanotify permission class listeners on this sb? > > > > > c) Are there any fanotify pre-content (a.k.a HSM) class listeners on this sb? > > > > > > > > > > I think that those questions are very relevant in the real world, because > > > > > a positive answer to (b) and (c) is quite rare in the real world, so the > > > > > overhead on the permission hooks could be completely eliminated in > > > > > the common case. > > > > > > > > > > If needed, we can further bisect the class counters per specific painful > > > > > events (e.g. FAN_ACCESS*), but there is no need to do that before > > > > > we see concrete benchmark results. > > ... > > > > > > Then I dislike how we have to specialcase superblock in quite a few places > > > > and add these wrappers and what not. This seems to be mostly caused by the > > > > fact that you directly embed fsnotify_mark_connector into fsnotify_sb_info. > > > > What if we just put fsnotify_connp_t there? I understand that this will > > > > mean one more pointer fetch if there are actually marks attached to the > > > > superblock and the event mask matches s_fsnotify_mask. But in that case we > > > > are likely to generate the event anyway so the cost of that compared to > > > > event generation is negligible? > > > > > > > > > > I guess that can work. > > > I can try it and see if there are any other complications. > > > > > > > And I'd allocate fsnotify_sb_info on demand from fsnotify_add_mark_locked() > > > > which means that we need to pass object pointer (in the form of void *) > > > > instead of fsnotify_connp_t to various mark adding functions (and transform > > > > it to fsnotify_connp_t only in fsnotify_add_mark_locked() after possibly > > > > setting up fsnotify_sb_info). Passing void * around is not great but it > > > > should be fairly limited (and actually reduces the knowledge of fsnotify > > > > internals outside of the fsnotify core). > > > > > > Unless I am missing something, I think we only need to pass an extra sb > > > arg to fsnotify_add_mark_locked()? and it does not sound like a big deal. > > > For adding an sb mark, connp arg could be NULL, and then we get connp > > > from sb->fsnotify_sb_info after making sure that it is allocated. > > > > Yes that would be another possibility but frankly I like passing the > > 'object' pointer instead of connp pointer a bit more. But we can see how > > the code looks like. > > Ok, here it is: > > https://github.com/amir73il/linux/commits/fsnotify-sbinfo/ > > I agree that the interface does end up looking better this way. Yep, the interface looks fine. I have left some comments on github regarding typos and some suspicious things. > I've requested to re-test performance on fsnotify-sbinfo. > > You can use this rebased branch to look at the diff from the > the previous patches that were tested by 0day: > > https://github.com/amir73il/linux/commits/fsnotify-sbconn/ > > If you have the bandwidth to consider those patches as candidates > for (the second half of?) 6.9 merge window, I can post them for review. Well, unless Linus does rc8, I don't think we should queue these for the merge window as it is too late by now. But please post them for review, I'll have a look. I can then push them to my tree early into a stable branch and you can base your patches on my branch. If the patches then need to go through VFS tree, Christian is fine with pulling my tree... Honza -- Jan Kara SUSE Labs, CR