From patchwork Sat May 7 21:29:43 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sergei Trofimovich X-Patchwork-Id: 764932 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter2.kernel.org (8.14.4/8.14.3) with ESMTP id p47LUxZM012264 for ; Sat, 7 May 2011 21:30:59 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755177Ab1EGVa5 (ORCPT ); Sat, 7 May 2011 17:30:57 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:42683 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755019Ab1EGVa4 (ORCPT ); Sat, 7 May 2011 17:30:56 -0400 Received: by bwz15 with SMTP id 15so3214775bwz.19 for ; Sat, 07 May 2011 14:30:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:from:to:cc:subject:date:message-id:x-mailer :in-reply-to:references; bh=27PIdzPkgPCX3DH1qqFyLw0OYqvO1FYcHZVn58Pl2eY=; b=oqmsKOBfqy60xgUEFF1fJ+83urJ3aO0yjQIRRXUhiiH+Bss9OS+2KkvDHqYRq9RgB3 3xyxiQKmYEMvyz/2lO4nN3DOO53tHEVQAEHbOnPFbEuUamSUmoqOnxR4KUd/U/YFxnpA LLJ8NwIiJfn6PRg1q7aDnt3NN4Zdd0yatKcFo= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references; b=SsBRuKU1KVSCEQZhqsZrVQ2Wx6JYl9THp6kB07D2o2C0X739H/GQB3YJogWMhhXVi0 7FVMMEaE+NJbNuphnC3D4rl3dS9KZp4UWy3sw9ZRug0x7qOLY0kYuiKjBpPr8l2G3DR/ YiYhYWObDojtEGf0BEwu5+x8VBaWQjv9lAGbs= Received: by 10.204.154.199 with SMTP id p7mr1704151bkw.114.1304803855218; Sat, 07 May 2011 14:30:55 -0700 (PDT) Received: from slyich@gmail.com ([178.125.175.156]) by mx.google.com with ESMTPS id q25sm2750031bkk.10.2011.05.07.14.30.52 (version=TLSv1/SSLv3 cipher=OTHER); Sat, 07 May 2011 14:30:54 -0700 (PDT) Received: by slyich@gmail.com (sSMTP sendmail emulation); Sun, 08 May 2011 00:30:50 +0300 From: slyich@gmail.com To: linux-btrfs@vger.kernel.org Cc: Chris Mason , Sergei Trofimovich Subject: [PATCH 3/4] btrfs: don't spin in shrink_delalloc if there is nothing to free Date: Sun, 8 May 2011 00:29:43 +0300 Message-Id: <1304803784-23756-2-git-send-email-slyfox@gentoo.org> X-Mailer: git-send-email 1.7.3.4 In-Reply-To: <1304803784-23756-1-git-send-email-slyfox@gentoo.org> References: <1304803784-23756-1-git-send-email-slyfox@gentoo.org> Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter2.kernel.org [140.211.167.43]); Sat, 07 May 2011 21:30:59 +0000 (UTC) Observed as a large delay when --mixed filesystem is filled up. Test example: 1. create tiny --mixed FS: $ dd if=/dev/zero of=2G.img seek=$((2048 * 1024 * 1024 - 1)) count=1 bs=1 $ mkfs.btrfs --mixed 2G.img $ mount -oloop 2G.img /mnt/ut/ 2. Try to fill it up: $ dd if=/dev/urandom of=10M.file bs=10240 count=1024 $ seq 1 256 | while read file_no; do echo $file_no; time cp 10M.file ${file_no}.copy; done Up to '200.copy' it goes fast, but when disk fills-up each -ENOSPC message takes 3 seconds to pop-up _every_ ENOSPC (and in usermode linux it's even more: 30-60 seconds!). (Maybe, time depends on kernel's timer resolution). No IO, no CPU load, just rescheduling. Some debugging revealed busy spinning in shrink_delalloc. Signed-off-by: Sergei Trofimovich Reviewed-by: Josef Bacik --- fs/btrfs/extent-tree.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 9ee6bd5..9f5fdd3 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -3425,6 +3425,10 @@ static int shrink_delalloc(struct btrfs_trans_handle *trans, if (reserved == 0) return 0; + /* nothing to shrink - nothing to reclaim */ + if (root->fs_info->delalloc_bytes == 0) + return 0; + max_reclaim = min(reserved, to_reclaim); while (loops < 1024) {