<html>
<head>
<style><!--
.hmmessage P
{
margin:0px;
padding:0px
}
body.hmmessage
{
font-size: 10pt;
font-family:Verdana
}
--></style>
</head>
<body class='hmmessage'>
hello,recently i had do a research about mpich2 to compare the "nemesis" and "shm" channel.in the research,first, i make install mpich2 with nemesis,and then make install with shm. my purpose is to compare the latency and bandwidth by using the two channel in a single SMP node.<BR>
the test enviroment is Intel(R) Xeon(R) CPU X5355 2.66GH,cache size : 4096 KB<BR>
and the test result shows that the bandwidth,when the mpi message size from 1-32Byte,the bandwidth shows similar;then the message size from 32-512B,the nemesis shows little better than shm;but after 512B to 1MB(my test use OSU benchmark,message size from 1Byte-4MB),the shm show more better than the nemesis,the peak is about 1800MBps(shm),but the nemesis is only 1100MBps;from 1MB to 4MB,the bandwidth in shm decrease rapidly,anyway it also better than the nemesis,when the message size come to 4MB,the nemesis and shm show the similar bandwidth.<BR>
my question is: why the shm show the more better performance than the nemesis? is it owing to the data transfer method or shm has some optimize functions ?<BR>
pls tell me ,thank you!<BR> <br /><hr />使用Messenger保护盾2.0，支持多账号登录！ <a href='http://im.live.cn/safe/' target='_new'>现在就下载！</a></body>
</html>