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 A6C68C25B06 for ; Mon, 15 Aug 2022 02:52:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229463AbiHOCwP (ORCPT ); Sun, 14 Aug 2022 22:52:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42550 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229533AbiHOCwN (ORCPT ); Sun, 14 Aug 2022 22:52:13 -0400 X-Greylist: delayed 564 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Sun, 14 Aug 2022 19:52:12 PDT Received: from synology.com (mail.synology.com [211.23.38.101]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C29F913DF4 for ; Sun, 14 Aug 2022 19:52:12 -0700 (PDT) Received: from localhost.localdomain (unknown [10.17.45.240]) by synology.com (Postfix) with ESMTPA id D2EAA2E550A5E; Mon, 15 Aug 2022 10:42:46 +0800 (CST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=synology.com; s=123; t=1660531367; bh=CbrwuBdZ1Bg1tixDuz5o/NB2QhoyjVqpY+azz61lXb0=; h=From:To:Cc:Subject:Date; b=XYnkNhLB/9eoCMRGR/E7RdNnN5YvzQZbtIfSTi9rR+4QfzB+bMX617zU4K7wjLVSV vJJi7wLQF9oA2wG2FtKsWmchcQEK5KlkwQkxJTXsqJb6kigi6of/qf5da5Id1qE7pb F6L+Y7tj+CWZ2+C3e7lXn/aty4rYOWaDfVSZNoRI= From: ethanlien To: linux-btrfs@vger.kernel.org Cc: cunankimo@gmail.com, Ethan Lien Subject: [PATCH] btrfs: remove unnecessary EXTENT_UPTODATE state in buffered I/O path Date: Mon, 15 Aug 2022 10:42:09 +0800 Message-Id: <20220815024209.26122-1-ethanlien@synology.com> X-Mailer: git-send-email 2.17.1 X-Synology-MCP-Status: no X-Synology-Spam-Flag: no X-Synology-Spam-Status: score=0, required 6, WHITELIST_FROM_ADDRESS 0 X-Synology-Virus-Status: no Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org 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 --- fs/btrfs/extent-io-tree.h | 4 ++-- fs/btrfs/extent_io.c | 3 --- 2 files changed, 2 insertions(+), 5 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..e0f0a39cd6eb 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); -- 2.17.1