OxY wrote:
----- Original Message ----- From: "Jin Guojun (VFFS)" <[EMAIL PROTECTED]>
To: "OxY" <[EMAIL PROTECTED]>
Cc: "Chuck Swiger" <[EMAIL PROTECTED]>; <freebsd-performance@freebsd.org>
Sent: Sunday, March 19, 2006 11:46 AM
Subject: Re: packet drop with intel gigabit / marwell gigabit
OxY wrote:
CPU utilization is 0% if apache is not running and 10-20%, when
running and
serving 30-40 concurrent downloads (traffic is 3-4MB/s on fxp0
interface)
Is the number 3-4MB/s for per stream or the total for all 30-40
streams?
Are these downloads sent to a disk?
it's a total, 30-40 streams get the files from two sata disks in raid1
....
First let's clear the notation -- Is 30MB/s (MBytes/s) = 240Mb/s
(Mbit/s) or MB/s means Mbits/s
If MB/s is MBytes/s and you also write this amount data to a disk,
plus other traffic on fxp0 to disk too,
then your problem may be bonded by memory bandwidth because CPU
utilization is low:
(240 + 24~32) x 2 is about 535 Mbit/s (some chipset/motherboard
has low memory BW for AMD)
If this is true, then this no thing you can tune. What does the
chipset (Motherboard) this machine have?
30MB/s is Megabytes/sec, currently i have 18-20MB/s peak and 15MB/s avg.
it's not 535Mbit/s, because i only download it to my machine, no upload.
disks are different from apache disks, these disks have own controller
in one pci slot.
the packet drop is 5-7% at 200Mbit iperf test, 100Mbit drop is around
zero.
i have <ASUS A7V8X> on motherboard which has VIA KT400 northbridge
http://uk.asus.com/products4.aspx?modelmenu=2&model=226&l1=3&l2=13&l3=62
Yes, this is one of problem chipset. I bought one about 3 years ago.
After one day testing, I returned it for changing a A7V600 (VIA KT600
chipset),
which is 30% more memory bandwidth than KT400. A7V600 can only receive max
604 Mb/s TCP, so You can imagine what the KT400 can do :-)
I do not have a record (because it is too bad), but taking minimum 25% off,
it probably about 420-430 Mb/s (50MB/s). Now you can do the math when the
machine also writing data to a disk (assume disk a fast enough). I would
expect
2/3 of 430 Mb/s, which is about 280~290 Mb/s (35 MB/s).
If you experiment these numbers, you are at there. No improvement you
can make
further.
i have an ABIT BE7
(http://www.abit.com.tw/page/uk/motherboard/motherboard_detail.php?pMODEL_NAME=BE7&fMTYPE=Socket%20478&pPRODINFO=Specifications)
resting somewhere, could it improve the network performance
with a P4-2.4GHZ(533FSB)?
(i don't want Intel-AMD flame :) )
AMD is good. As I mentioned earlier, it is motherboard shipset make's
problem.
I like AMD CPU, and I amd writing from A7V600 with AMD XP 2100+ :-)
The ABIT motherboard has an Intel 845 chipset, which has very good
memory bandwidth.
You should be able to saturate your GigE interface on this motherboard.
If you have problem to obtain the performance, we can tune it .
Good luck!
-Jin
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