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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9AA5AC28B2B for ; Fri, 19 Aug 2022 17:24:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350785AbiHSRYE (ORCPT ); Fri, 19 Aug 2022 13:24:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48172 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350654AbiHSRXa (ORCPT ); Fri, 19 Aug 2022 13:23:30 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 85C6115078E for ; Fri, 19 Aug 2022 09:42:22 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A6B65B827FA for ; Fri, 19 Aug 2022 16:42:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ECF15C433C1; Fri, 19 Aug 2022 16:42:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1660927335; bh=i6IpbQgcnxWdZo0Q1+M1VJ6oaZ2cChhdVBcYVkD4UbM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LVLBEOEEwE/ItxIY4hCZLWuaNKLWue4QU7JR3hUJV9ujiQCCp9ytKbEj+iZ5MhZk5 jHLSKl2xwPP59LV+hffq38H9azJIeOMSMJp63Q8uMYmXPE6un0+SNwXOJLX0L/vpBq Stk98A3XIVIhN49IU1TZBWvdAh50oAxyq9gW5UZsJuXcX07UUAZPNaleHBxDFMcNvY 2h/TjzAM6RZcPwpccKdbqfDCLvvXo62eGldRE/qDKki5E8ZNrz2z7Cf5Q8ICWMntWk fUURERvReAJyGxgStYYv/wPmKa5NNhR+pwRd4qWdShuobR6cpYyKm1s63ZovHnCv3r 4CId1gZ4Roc8w== Date: Fri, 19 Aug 2022 17:42:12 +0100 From: Filipe Manana To: ethanlien Cc: linux-btrfs@vger.kernel.org, cunankimo@gmail.com Subject: Re: [PATCH v2] btrfs: remove unnecessary EXTENT_UPTODATE state in buffered I/O path Message-ID: <20220819164212.GA3012163@falcondesktop> References: <20220819024408.9714-1-ethanlien@synology.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220819024408.9714-1-ethanlien@synology.com> Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Fri, Aug 19, 2022 at 10:44:08AM +0800, ethanlien wrote: > From: Ethan Lien > > After we copied data to page cache in buffered I/O, we > 1. Insert a EXTENT_UPTODATE state into inode's io_tree, by > endio_readpage_release_extent(), set_extent_delalloc() or > set_extent_defrag(). > 2. Set page uptodate before we unlock the page. > > But the only place we check io_tree's EXTENT_UPTODATE state is in > btrfs_do_readpage(). We know we enter btrfs_do_readpage() only when we > have a non-uptodate page, so it is unnecessary to set EXTENT_UPTODATE. > > For example, when performing a buffered random read: > > fio --rw=randread --ioengine=libaio --direct=0 --numjobs=4 \ > --filesize=32G --size=4G --bs=4k --name=job \ > --filename=/mnt/file --name=job > > Then check how many extent_state in io_tree: > > cat /proc/slabinfo | grep btrfs_extent_state | awk '{print $2}' > > w/o this patch, we got 640567 btrfs_extent_state. > w/ this patch, we got 204 btrfs_extent_state. > > Maintaining such a big tree brings overhead since every I/O needs to insert > EXTENT_LOCKED, insert EXTENT_UPTODATE, then remove EXTENT_LOCKED. And in > every insert or remove, we need to lock io_tree, do tree search, alloc or > dealloc extent states. By removing unnecessary EXTENT_UPTODATE, we keep > io_tree in a minimal size and reduce overhead when performing buffered I/O. > > Signed-off-by: Ethan Lien > Reviewed-by: Robbie Ko > --- > > V2: Remove set_extent_uptodate() from btrfs_get_extent(), and when we found > a inline extent, set page uptodate in btrfs_do_readpage(). Yep, that was what I had in mind. Thanks for trying it out. I've given it some testing, including a full run of fstests just to confirm I hadn't missed something. Looks good, so: Reviewed-by: Filipe Manana Thanks. > > fs/btrfs/extent-io-tree.h | 4 ++-- > fs/btrfs/extent_io.c | 16 +--------------- > fs/btrfs/inode.c | 2 -- > 3 files changed, 3 insertions(+), 19 deletions(-) > > diff --git a/fs/btrfs/extent-io-tree.h b/fs/btrfs/extent-io-tree.h > index c3eb52dbe61c..53ae849d0248 100644 > --- a/fs/btrfs/extent-io-tree.h > +++ b/fs/btrfs/extent-io-tree.h > @@ -211,7 +211,7 @@ static inline int set_extent_delalloc(struct extent_io_tree *tree, u64 start, > struct extent_state **cached_state) > { > return set_extent_bit(tree, start, end, > - EXTENT_DELALLOC | EXTENT_UPTODATE | extra_bits, > + EXTENT_DELALLOC | extra_bits, > 0, NULL, cached_state, GFP_NOFS, NULL); > } > > @@ -219,7 +219,7 @@ static inline int set_extent_defrag(struct extent_io_tree *tree, u64 start, > u64 end, struct extent_state **cached_state) > { > return set_extent_bit(tree, start, end, > - EXTENT_DELALLOC | EXTENT_UPTODATE | EXTENT_DEFRAG, > + EXTENT_DELALLOC | EXTENT_DEFRAG, > 0, NULL, cached_state, GFP_NOFS, NULL); > } > > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c > index bfae67c593c5..7e082770a088 100644 > --- a/fs/btrfs/extent_io.c > +++ b/fs/btrfs/extent_io.c > @@ -2924,9 +2924,6 @@ static void endio_readpage_release_extent(struct processed_extent *processed, > * Now we don't have range contiguous to the processed range, release > * the processed range now. > */ > - if (processed->uptodate && tree->track_uptodate) > - set_extent_uptodate(tree, processed->start, processed->end, > - &cached, GFP_ATOMIC); > unlock_extent_cached_atomic(tree, processed->start, processed->end, > &cached); > > @@ -3718,20 +3715,9 @@ static int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, > continue; > } > /* the get_extent function already copied into the page */ > - if (test_range_bit(tree, cur, cur_end, > - EXTENT_UPTODATE, 1, NULL)) { > - unlock_extent(tree, cur, cur + iosize - 1); > - end_page_read(page, true, cur, iosize); > - cur = cur + iosize; > - pg_offset += iosize; > - continue; > - } > - /* we have an inline extent but it didn't get marked up > - * to date. Error out > - */ > if (block_start == EXTENT_MAP_INLINE) { > unlock_extent(tree, cur, cur + iosize - 1); > - end_page_read(page, false, cur, iosize); > + end_page_read(page, true, cur, iosize); > cur = cur + iosize; > pg_offset += iosize; > continue; > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index f0c97d25b4a0..639edbcce9fe 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -7031,8 +7031,6 @@ struct extent_map *btrfs_get_extent(struct btrfs_inode *inode, > } > flush_dcache_page(page); > } > - set_extent_uptodate(io_tree, em->start, > - extent_map_end(em) - 1, NULL, GFP_NOFS); > goto insert; > } > not_found: > -- > 2.17.1 >