Serious performance issues

[Tommi Virtanen <tv@tv.debian.net>]

Hi. I have a Shuttle box with an AMD Athlon XP 2200+ and 1GB of RAM.
I'm normally running it with Debian sarge/sid and kernel 2.6.10-1-k7,
as built by Debian. I want to use Xen on it. I built a xen0 kernel
which is as close to the Debian kernel as I can (no power management,
no HPET timers, broken ISA drivers disabled), disabled /lib/tls, and
booted with the new kernel.

Everything works. I can run domUs as I want. But, the performance is
horrible, even with just dom0 running.

I tested the disk, it still transfers ~50MB/s. I don't seem to be
suffering from PIO mode. Also, things running from RAM cache are as
slow as from disk.

I ran some of the lmbench tests both under xen and with native linux.
Here are the results, with the "-" lines from xen and "+" lines from
native linux. The results are pretty poor, and so is the feel of the
machine under xen.

Any hints on what to try next?


bw_mem
-0.131072 1068.95
+0.131072 4409.00

bw_pipe
-Pipe bandwidth: 85.42 MB/sec
+Pipe bandwidth: 989.19 MB/sec

bw_unix
-AF_UNIX sock stream bandwidth: 104.75 MB/sec
+AF_UNIX sock stream bandwidth: 968.87 MB/sec

lat_ctx
-"size=0k ovr=3.15
-10 13.95
+"size=0k ovr=1.09
+10 0.94

lat_fcntl
-Fcntl lock latency: 43.2246 microseconds
+Fcntl lock latency: 5.4676 microseconds

lat_fifo
-FIFO latency: 32.4076 microseconds
+FIFO latency: 3.3622 microseconds

lat_fs
-0k     1000    18563   31549
-1k     1000    6426    17887
-4k     1000    6583    17826
-10k    1000    3084    14989
+0k     1000    63666   92541
+1k     1000    24125   51193
+4k     1000    25863   52089
+10k    1000    12533   41564

lat_pipe
-Pipe latency: 31.0475 microseconds
+Pipe latency: 5.4833 microseconds

lat_proc
-Process fork+exit: 789.2857 microseconds
+Process fork+exit: 113.7347 microseconds

lat_select
-Select on 200 tcp fd's: 46.8159 microseconds
+Select on 200 tcp fd's: 12.9369 microseconds

lat_syscall
-Simple syscall: 0.6188 microseconds
+Simple syscall: 0.1547 microseconds

lat_unix
-AF_UNIX sock stream latency: 61.1547 microseconds
+AF_UNIX sock stream latency: 21.7704 microseconds


-------------------------------------------------------
SF email is sponsored by - The IT Product Guide
Read honest & candid reviews on hundreds of IT Products from real users.
Discover which products truly live up to the hype. Start reading now.
http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click