Re: Sarge Performance
On 5/21/05, Lars Roland <lroland@gmail.com> wrote:
> Hi all
>
> I just replaced my company anti-virus/anti-spam mail gateway from a
> Redhat 7.3 with kernel 2.4.24 to Debian Sarge with kernel 2.6.8.1. I
> had hoped that this transition would lead to better performance (new
> perl, better drivers in the kernel and so on) but the performance has
> instead drooped about 30%.
>
Well it seamed that at least part of the problem was related to the
new kernel. On my old Redhat system my Broadcom tg3 Ethernet card was
running 100mbit with a tx queue length of 100. On kernel 2.6.8.1 it
was running 1000Mbit with tx queue length of 1000.
Setting the length to 100 again using:
ifconfig eth0 txqueuelen 100
Made the load drop immediately and also harddisk performance improved: eg.
--------------------------------
txgueue length: 1000
hdparm -t /dev/sda
/dev/sda:
Timing buffered disk reads: 12 MB in 3.40 seconds = 3.53 MB/sec
--------------------------------
and
--------------------------------
txgueue length: 100
hdparm -t /dev/sda
/dev/sda:
Timing buffered disk reads: 152 MB in 3.40 seconds = 44.74 MB/sec
--------------------------------
So now the load looks ok, still the old Redhat is holding its head
above but now it is only with 10%. This may be due to further bugs in
the tg3 driver that hopefully a new kernel will fix - if not then I
must fill a bug report and send it to the driver developers, it can
not be intently that there driver messes up system performance that
much because of its default queue length.
Regards.
Lars Roland
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