Re: [Xen-devel] httpd persormance in Xen environment.

[nayden <nayden@xxxxxxxxx>]

I am getting the follwoing messages from dmesg in Dom1, which are
rather suspicious.

TCP: drop open request from 192.168.0.14/26284
printk: 8712 messages suppressed.
TCP: drop open request from 192.168.0.14/36324
printk: 8921 messages suppressed.
TCP: drop open request from 192.168.0.13/45416

192.168.0.13/14 are machines on which I am running httperf.

Since I am getting similar messages on native linux this probmel is
one thing that I am investigating.

nayden
On Sat, 4 Dec 2004 08:24:17 -0000, Ian Pratt <m+ian.pratt@xxxxxxxxxxxx> wrote:
> > 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.
> 
> Have you enabled connection tracking in the dom0 kernel as this can slow
> things down? Does 'dmesg' show anything being logged?
> 
> [Just to be sure, are you getting the poor performance with non
> persistent connections, right?]
> 
> Ian
> 
> 
> 
> > 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 checked.
> >
> > 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  2.6.8.1-xen0 and 2.6.8.1-xenU.
> > (perhaps the first place to check?)
> >
> > nayden
> >
> > 
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