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[Xen-devel] httpd persormance in Xen environment.

  • To: Xen Devel Mailing List <xen-devel@xxxxxxxxxxxxxxxxxxxxx>
  • From: nayden <nayden@xxxxxxxxx>
  • Date: Fri, 3 Dec 2004 06:48:35 -0700
  • Delivery-date: Fri, 03 Dec 2004 13:49:55 +0000
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I am stresstesting httpd (Apache 1.3.31) under native linux and
xenolinux on order to evaluate the server performance in both
environments.  The hardware for each subsequent runs is identical, and
I also tried to keep the software configuration as similar as possible
(same versions of packages installed, same services enabled/disabled
etc.)  To test the performance of httpd I am using httperf with either
persistend and non-persistent connections.  When persistent
connections are enebled, I get very close performance on xenolinux to
native Linux, but when they are disabled the server performance over
xenolinux really suffers.  To give you a rough estimates how bad it is
here are some numbers.

persistent enabled   reply rate native                  xenolinux
4000 req/sec                   3900 rep/sec                700 rep/sec
persistent disabled         
4000 req/sec                   3950 rep/sec                3950 rep/sec

I understand why the case of persistent connections performs better
than the non-persistent, however in the former case httpd performance
under xenolinux is buffeling to me.

I suspect it is due to misconfiguration rather than xen issue and I
will appreciate if some of you provide any advices on what needs to be

The modifications that I have made to the kernel configuration of
linux, dom0 and dom0 are the following
# enable tcp time-wait recycling
echo 1 > /proc/sys/net/ipv4/tcp_tw_recycle

#disable tcp timestamps 
echo 0 > /proc/sys/net/ipv4/tcp_timestamps

# increase the number of local ports that are available for use
echo 5000 65535 > /proc/sys/net/ipv4/ip_local_port_range

max number of open file descriptors for each processor is increased to 32K. 

Native linux runs FC2 2.8.1 kernel that was compiled with different
configuration than and (perhaps the first
place to check?)


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