MySQL performance concern

[Rumen Telbizov]

Hello everyone,

I am experimenting with MySQL running on FreeBSD and comparing with another
(older) setup running on a Linux box.
My results show that performance on Linux is significantly better than
FreeBSD although the hardware is weaker.
I'd appreciate your comments and ideas.

Here's the setup:

1) FreeBSD 8.1-STABLE amd64 (Tue Sep 14 15:29:22 PDT 2010) running on a
SuperMicro machine with 2 x Dual Core
Xeon E5502 1.87Ghz ; 4 x SAS 15K in RAID10 setup under ZFS (two mirrored
pairs) and 2 x SSD X25-E partitioned
for: 8G for ZIL and the rest for L2ARC; 16G ram with 8 of them given to
mysql and tons of free.

2) Linux Gentoo with 3 SATA disks in hardware RAID5 with similar
cpu/motherboard and same memory size.

The sole application that runs is a python script which inserts a batch of
lines at a time. Only myisam is used as a format.
Here's the problem: On the Linux box it manages to push around
*5800*inserts/second while on the FreeBSD box
it's only *4000/*second.

MySQL version is 5.1.51

During this load the disk subsystem on FreeBSD is pretty much idle (both the
SSDs and the SAS disks). CPU utilization
contributed to mysqld is only around 30%. So I am clearly heavily
under-utilizing the hardware.
Linuxthreads support for 64bit architectures is not available so I couldn't
try that but aside from that I tried recompiling
mysql with all the different Makefile options available without any effect.
Changing the recordsize in zfs to 8K doesn't make any difference.
Tried percona binary without any luck.

Let me know what additional information would be useful and I'll provide it
here.

Thank you in advance for your comments and suggestions.

Cheers,
Rumen Telbizov