From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?B?SmFuIEt1bmRyw6F0?= Subject: poor I/O performance on domU Date: Thu, 13 Jan 2005 17:06:48 +0100 Message-ID: <41E69C98.7090804@fzu.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: xen-devel-admin@lists.sourceforge.net Errors-To: xen-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: xen-devel List-Id: xen-devel@lists.xenproject.org Hi, comparing disk I/O performance of domain0 running gentoo and unprivileged domain with ttylinux (tried multiple times, results differ in ~ 1sec range): In domain0: zirafa ~ # time dd if=/dev/hda of=/dev/null bs=1M count=500 500+0 records in 500+0 records out real 0m27.344s user 0m0.000s sys 0m2.280s zirafa ~ # hdparm -t /dev/hda /dev/hda: Timing buffered disk reads: 56 MB in 3.03 seconds = 18.48 MB/sec ----------------------------- And for unprivileged domains: root@tiny ~ # time dd if=/dev/sdb1 of=/dev/null bs=1M count=500 500+0 records in 500+0 records out real 0m41.962s user 0m0.010s sys 0m1.920s root@tiny ~ # hdparm -t /dev/sdb1 /dev/sdb1: Timing buffered disk reads: 64 MB in 5.32 seconds = 12.03 MB/sec ioctl 00001261 not supported by Xen blkdev hdparm: BLKFLSBUF: Function not implemented ioctl 0000031f not supported by Xen blkdev hdparm: HDIO_DRIVE_CMD: Function not implemented I've tried exporting /dev/hda as /dev/sdb, /dev/sdb1 and /dev/hda, all of them in read-only mode. Results look very similar, only `hdparm -t /dev/hda` from domainU complains bit more: root@tiny ~ # hdparm -t /dev/hda /dev/hda: Timing buffered disk reads: 64 MB in 5.38 seconds = 11.90 MB/sec ioctl 00001261 not supported by Xen blkdev hdparm: BLKFLSBUF: Function not implemented ioctl 0000031f not supported by Xen blkdev hdparm: HDIO_DRIVE_CMD: Function not implemented [XEN:vbd_update:drivers/xen/blkfront/blkfront.c:194] > [XEN:vbd_update:drivers/xen/blkfront/blkfront.c:195] < I'm using some older version of Xen/2, compiled on 14 Nov 2004, machine is celeron/466 with 256MB of RAM, 64 for dom0. ttylinux.conf: kernel = "/boot/vmlinuz-2.6.9-xenU" memory = 64 name = "ttylinux" nics = 1 ip = "10.18.6.10" disk = ['file:/home/storage/ttylinux-xen,sda1,r','phy:hda,hda,r'] root = "/dev/sda1 ro" ttylinux's rootfs is exported from ext3 fs via loopback device, could it be the cause of troubles? -jkt -- cd /local/pub && more beer > /dev/mouth ------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It's fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt