Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264231AbTKKFGi (ORCPT ); Tue, 11 Nov 2003 00:06:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264259AbTKKFGi (ORCPT ); Tue, 11 Nov 2003 00:06:38 -0500 Received: from nat-68-172-17-106.ne.rr.com ([68.172.17.106]:35831 "EHLO trip.jpj.net") by vger.kernel.org with ESMTP id S264231AbTKKFGg (ORCPT ); Tue, 11 Nov 2003 00:06:36 -0500 Subject: Re: I/O issues, iowait problems, 2.4 v 2.6 From: Paul Venezia To: Andrew Morton Cc: linux-kernel@vger.kernel.org In-Reply-To: <20031110205443.6422259f.akpm@osdl.org> References: <1068519213.22809.81.camel@soul.jpj.net> <20031110195433.4331b75e.akpm@osdl.org> <1068523328.25805.97.camel@soul.jpj.net> <20031110202819.7e7433a8.akpm@osdl.org> <1068524657.25804.110.camel@soul.jpj.net> <20031110205443.6422259f.akpm@osdl.org> Content-Type: text/plain Organization: Message-Id: <1068526547.22800.131.camel@soul.jpj.net> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.4 Date: 10 Nov 2003 23:55:48 -0500 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3729 Lines: 72 On Mon, 2003-11-10 at 23:54, Andrew Morton wrote: > > 0 10 0 1146444 18940 286856 0 0 0 2106 21450 25860 4 14 37 45 > > OK, the IO rates are obviously very poor, and the context switch rate is > suspicious as well. Certainly, testing with the single disk would help. I'll get to that as soon as I can. > > But. If the workload here was a simple dd of /dev/zero onto a regular > file then why on earth is the pagecache size not rising? This vmstat output was shot when I was first noticing this problem. The nbench tests were running at the time. Seems to indicate the same as below. > Could you please > do: > > rm foo > cat /dev/zero > foo > > and rerun the `vmstat 1' trace? Make sure that after the big initial jump, > the `cache' column is increasing at a rate equal to the I/O rate. Thanks. When I first ran this test, I killed it after 45s or so, noting that the vmstat output didn't look right. I then deleted the sample file. The file no longer existed, but the rm didn't exit in a timely fashion, the CPUs were at 100% iowait, the load was rising and vmstat was showing a consistent pattern of 5056 blocks out every two seconds. I rebooted and shot these, starting 5 seconds before the cat: 0 0 0 1474524 7084 42420 0 0 0 0 1033 47 0 0 100 0 0 0 0 1474524 7084 42420 0 0 0 0 1031 38 0 0 100 0 0 0 0 1474524 7084 42420 0 0 0 0 1016 12 0 0 100 0 1 0 0 1373716 7184 140376 0 0 0 0 1020 14 0 10 90 0 1 2 0 1166548 7392 341652 0 0 8 18836 1028 56 0 21 43 36 1 2 0 994132 7556 509312 0 0 4 1696 1030 63 0 17 27 56 1 2 0 867732 7684 632264 0 0 4 2400 1033 65 0 12 27 60 0 3 0 817748 7732 680700 0 0 4 9632 1033 66 0 5 27 67 0 4 0 817748 7732 680700 0 0 0 0 1029 47 0 0 25 75 2 2 0 817748 7732 680700 0 0 0 5372 1032 48 0 0 25 75 0 4 0 810324 7740 688104 0 0 0 104 1032 49 0 1 25 74 0 4 0 810324 7740 688104 0 0 0 0 1029 48 0 0 25 75 0 4 0 810324 7740 688104 0 0 0 4892 1038 54 0 0 25 75 0 4 0 810324 7740 688104 0 0 0 0 1024 46 0 0 25 75 0 4 0 793492 7756 704544 0 0 0 9952 1033 52 0 2 25 73 0 4 0 793492 7756 704544 0 0 0 0 1032 48 0 0 25 75 0 4 0 793428 7756 704544 0 0 0 0 1031 48 0 0 25 75 0 4 0 793428 7756 704544 0 0 0 0 1028 52 0 0 25 75 0 4 0 768276 7780 729136 0 0 0 4996 1032 51 0 2 25 72 0 4 0 768276 7780 729136 0 0 0 0 1035 46 0 0 25 75 0 4 0 768276 7780 729136 0 0 0 4892 1026 50 0 0 25 75 0 4 0 768276 7780 729136 0 0 0 0 1037 46 0 0 25 75 0 4 0 763988 7784 733212 0 0 0 5060 1032 56 0 0 25 75 0 4 0 763988 7784 733212 0 0 0 0 1032 46 0 0 25 75 0 4 0 763988 7784 733212 0 0 0 4892 1033 48 0 0 25 75 0 4 0 763988 7784 733212 0 0 0 0 1029 50 0 0 25 75 0 4 0 751316 7796 745508 0 0 0 5060 1039 52 0 1 25 74 0 4 0 751316 7796 745508 0 0 0 0 1025 52 0 0 25 75 Very similar. -Paul - 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/