This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-users] DomU slower with smp?

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] DomU slower with smp?
From: "Janusz Ulanowski" <janul666@xxxxxxxxx>
Date: Thu, 15 May 2008 00:18:47 +0100
Delivery-date: Wed, 14 May 2008 16:19:19 -0700
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; bh=Nwr8r1JWFKIcLfdgvB6tnsBS43dpDK6IxDYp40xlZ+U=; b=c7wxqTt0gnXhxDNgVC8e3Qh9vqRcBw/obcwkYJ0eeIYDmWOsswNr3UOboeLNlshUyrm7QPhl1QnIPE3YOf3Z9EUsIhh0F74w+iKs8nXqSF8qzIR/NFqHX1Nsg8VEnioPM5l4lJoxL3ZqRVyNNzyQMHxT+cwgAKp3WsyuGeQfZnE=
Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; b=NYBcGPg192Ljpvfoy0iss3ZIz0Q02e1dPCbN3Ch3dQH6qg7sTmwMsaE03Mn1EaJGtmu0+cOHbN78t9ZvhXqR6pSipZFVNO6rCaKB9GMOu7WAjZC/MTv5EVyprm0tirHeSOV6LNf2brrtq7XPjX6dK9hdiFxWRlVCtattwBQSRjM=
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <4cdb57b90805141557r12ec2272kc7763154aeedb307@xxxxxxxxxxxxxx>
List-help: <mailto:xen-users-request@lists.xensource.com?subject=help>
List-id: Xen user discussion <xen-users.lists.xensource.com>
List-post: <mailto:xen-users@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=unsubscribe>
References: <4cdb57b90805140435g58427e58w56848049ee027f9a@xxxxxxxxxxxxxx> <AF358A0C5B36EC4486D1A764A171904D034C9989@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> <4cdb57b90805141557r12ec2272kc7763154aeedb307@xxxxxxxxxxxxxx>
Sender: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
I fact I tested with 1GB RAM in DomU
When I increased to 9GB the result looks much better:
real    2m59.121s

sorry for confusing...
this is 64bit architecture so maybe that's why.

2008/5/14 Janusz Ulanowski <janul666@xxxxxxxxx>:
Thanks for your answer.
I've done as you said.
Unfortunatelly no difference.
it goes worse when I increase file size or threads number.


time iozone -t 40 -r 2m -s 100m -m -R
DomU with four cpus (each from different core)
 real    6m19.300s
DomU with one cpu
 real 3m32.651s
 real    2m37.418s

# xm info
host                   : xxxx
release                :
version                : #2 SMP Mon May 12 13:19:28 IST 2008
machine                : x86_64
nr_cpus                : 16
nr_nodes               : 1
cores_per_socket       : 4
threads_per_core       : 1
cpu_mhz                : 2393
hw_caps                : bfebfbff:20100800:00000000:00000140:0004e3bd:00000000:00000001
total_memory           : 65530
free_memory            : 12
node_to_cpu            : node0:0-15
xen_major              : 3
xen_minor              : 2
xen_extra              : .1
xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64
xen_scheduler          : credit
xen_pagesize           : 4096
platform_params        : virt_start=0xffff800000000000
xen_changeset          : Fri May 02 14:23:07 2008 +0100 16888:9733f681d5c5
cc_compiler            : gcc version 4.1.3 20080114 (prerelease) (Debian 4.1.2-19)
cc_compile_by          : root
cc_compile_domain      : lan
cc_compile_date        : Fri May  9 14:41:37 IST 2008
xend_config_format     : 4

Thanks in advance.

2008/5/14 Apparao, Padmashree K <padmashree.k.apparao@xxxxxxxxx>:

The SMP case may be suffering because of context switching.

Can you run the SMP by affintizing the vcpus to specific cores


Vcpu on core 1

Vcpu2 on core 2

Vcpu3 on core 3 etc





From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Janusz Ulanowski
Sent: Wednesday, May 14, 2008 4:36 AM
To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] DomU slower with smp?


I just made simple peformance test with iozone tool on xen 3.2.1.

time iozone -t 20 -r 2m -s 100m -m -R


Dom0 - lvm(XFS) : real    1m35.670s

DomU -  2m46.963s
cpus = "4-7"

DomU - 1m53.772s
cpus = "8"

It seems DomU  is much slower if using more than one cpu.

am I right?


Xen-users mailing list
<Prev in Thread] Current Thread [Next in Thread>