Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755383Ab0BHAHo (ORCPT ); Sun, 7 Feb 2010 19:07:44 -0500 Received: from borg.medozas.de ([188.40.89.202]:37279 "EHLO borg.medozas.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754549Ab0BHAHn (ORCPT ); Sun, 7 Feb 2010 19:07:43 -0500 Date: Mon, 8 Feb 2010 01:07:40 +0100 (CET) From: Jan Engelhardt To: Jens Axboe cc: Linux Kernel Mailing List Subject: Re: kswapd continuously active In-Reply-To: Message-ID: References: <20100125130627.GO13771@kernel.dk> <20100205130002.GI1025@kernel.dk> <20100205131220.GK1025@kernel.dk> User-Agent: Alpine 2.01 (LSU 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1901 Lines: 44 On Sunday 2010-02-07 11:50, Jan Engelhardt wrote: >On Friday 2010-02-05 14:24, Jan Engelhardt wrote: >>>> The ext4 filesystem is already mounted with barrier=0. If there >>>> is any block-level barriers I also can turn off, what would be >>>> the command? >>> >>>barrier=0 is enough. I do wonder why your writeback rate is that slow, >>>then. The disk has write back caching enabled? >> >>Yes, that seems to be the case at least. In fact the box is all fluffy >>when nobody runs sync(1), which is what makes it so strange. >> >>sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't >>support DPO or FUA > >Here is an alternate trace that just happened. > >INFO: task flush-8:0:343 blocked for more than 120 seconds. >"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. >flush-8:0 D 0000000000555930 6664 343 2 0x18000000000 >Call Trace: > [00000000005555f4] start_this_handle+0x324/0x4b0 > [0000000000555930] jbd2_journal_start+0x94/0xc0 > [000000000052ddb8] ext4_da_writepages+0x1e0/0x460 > [000000000049bf30] do_writepages+0x28/0x48 > [00000000004e6d58] writeback_single_inode+0xf0/0x330 > [00000000004e7b24] writeback_inodes_wb+0x4c8/0x5d8 > [00000000004e7da4] wb_writeback+0x170/0x1ec > [00000000004e8074] wb_do_writeback+0x188/0x1a4 > [00000000004e80b8] bdi_writeback_task+0x28/0xa0 > [00000000004a76c8] bdi_start_fn+0x64/0xc4 > [0000000000475f84] kthread+0x58/0x6c > [000000000042ade0] kernel_thread+0x30/0x48 > [0000000000475ee0] kthreadd+0xb8/0x104 Could it be that there is something synchronize_rcu()-like in the game that — as a result of how RCU works — just takes ages with 24 VCPUs? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/