From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: Strange MySQL behaviour Date: Thu, 28 Jul 2011 10:34:12 +0300 Message-ID: <4E3110F4.3000503@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: Boris Dolgov Return-path: Received: from mx1.redhat.com ([209.132.183.28]:47990 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750782Ab1G1HeS (ORCPT ); Thu, 28 Jul 2011 03:34:18 -0400 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On 07/28/2011 02:25 AM, Boris Dolgov wrote: > Hello! > > I am using Fedora 14 with kernel and qemu-kvm from Fedora 15: > [root@serv ~]# qemu-kvm --help | head -1 > QEMU emulator version 0.14.0 (qemu-kvm-0.14.0), Copyright (c) > 2003-2008 Fabrice Bellard > [root@serv ~]# uname -a > Linux serv 2.6.38.8-35.fc15.x86_64 #1 SMP Wed Jul 6 13:58:54 UTC 2011 > x86_64 x86_64 x86_64 GNU/Linux > > I have a guest with latest CentOS6: > [root@localhost ~]# uname -a > Linux localhost.localdomain 2.6.32-71.29.1.el6.x86_64 #1 SMP Mon Jun > 27 19:49:27 BST 2011 x86_64 x86_64 x86_64 GNU/Linux > > When I try to load a small MySQL database dump (nearly 10k lines), it > loads a lot of time. > Guest cpu states: > Cpu(s): 0.3%us, 0.6%sy, 0.0%ni, 61.9%id, 37.2%wa, 0.0%hi, 0.0%si, 0.0%st > MySQL Processlist: > mysql> show full processlist; > +----+------+-----------+--------+---------+------+---------------+------------------------------------------------------------+ > | Id | User | Host | db | Command | Time | State | > Info | > +----+------+-----------+--------+---------+------+---------------+------------------------------------------------------------+ > | 4 | root | localhost | NULL | Query | 0 | NULL | > show full processlist | > | 11 | root | localhost | zabbix | Query | 0 | freeing items | > INSERT INTO applications VALUES (41,10002,'Performance',0) | > Guest top: > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND > 1330 mysql 20 0 560m 29m 5900 S 1.3 6.0 0:05.61 mysqld > 336 root 20 0 0 0 0 D 0.7 0.0 0:02.39 kdmflush Looks like you are blocked on disk. What does iostat say about disk utilization (in both guest and host)? > 1367 root 20 0 14928 1212 924 S 0.7 0.2 0:08.42 top > 355 root 20 0 0 0 0 D 0.3 0.0 0:03.34 > jbd2/dm-0-8 > 1421 root 20 0 14932 1220 920 R 0.3 0.2 0:00.01 top > > Guest is installed inside LVM. > > Host cpu states: > Cpu(s): 2.3%us, 4.0%sy, 0.0%ni, 93.1%id, 0.4%wa, 0.0%hi, 0.1%si, 0.0%st > > QEMU command: > /usr/bin/qemu-kvm -enable-kvm -name VM7 -nographic -vnc 0.0.0.0:7 -vga > std -m 512 -smp 4 -boot c -pidfile /home/vms/run/7.pid -monitor > unix:/home/vms/run/7.monitor,server,nowait -serial > unix:/home/vms/run/7.serial,server,nowait -net > nic,vlan=0,macaddr=FE:E1:DE:AD:00:07,model=virtio -net > tap,vlan=0,ifname=tap_7_0,script=/home/vms/ifup,downscript=/home/vms/ifdown > -drive media=disk,if=virtio,index=0,file=/dev/vg0/cent6,cache=none,boot=on > > I can provide any additional debug information. > > What is the reason of this behaviour? Likely, slow disk flushes. Try s/cache=none/cache=unsafe/ as an experiment. Does it help? Try s/cache=none/cache=none,aio=native/. Does it help? This one is safe, you can keep it if it works. -- error compiling committee.c: too many arguments to function