<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv=Content-Type content="text/html; charset=us-ascii">
<meta name=Generator content="Microsoft Word 12 (filtered medium)">
<style>
<!--
/* Font Definitions */
@font-face
{font-family:SimSun;
panose-1:2 1 6 0 3 1 1 1 1 1;}
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:SimSun;
panose-1:2 1 6 0 3 1 1 1 1 1;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
text-align:justify;
font-size:10.5pt;
font-family:"Calibri","sans-serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:"Calibri","sans-serif";
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:72.0pt 90.0pt 72.0pt 90.0pt;}
div.WordSection1
{page:WordSection1;}
-->
</style>
<!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang=ZH-CN link=blue vlink=purple style='text-justify-trim:punctuation'>
<div class=WordSection1>
<p class=MsoNormal><span lang=EN-US>KVM performance is very poor?<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>I have tested a simple IO/CPU mixture
testcase under both RHEL5/Xen and RHEL6/KVM guest.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>The hardware configuration is DELL PE2950
with 8G CPU, E5130*2, 8G RAM, PERC 5i, 146G*3 RAID5 for virtualization pool.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Each guest takes 4 VPUS and 2G RAM.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>It seems that KVM is very slow than Xen.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>The test program spawns 10 threads, the
threads concurrently read a block device sequentially by <o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>32k block size. It also calculates the
crc32 and md5 checksum with each read request.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>I use O_DIRECT to avoid the influence of cache.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Total data size is 3.2G<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Under the naked machine, both RHEL5 and
RHEL6 can get 250M/s,<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>XEN guest can get 240M/s<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>KVM guest can get 120M/s<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US> Regards<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US> Kirby Zhou<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
</div>
</body>
</html>