packet drop with intel gigabit / marwell gigabit

OxY oxy at
Sun Mar 19 11:04:15 UTC 2006

----- Original Message ----- 
From: "Jin Guojun (VFFS)" <g_jin at>
To: "OxY" <oxy at>
Cc: "Chuck Swiger" <cswiger at>; <freebsd-performance at>
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

>> i measured the network performance with 'iperf' util, started the server 
>> on my box
>> and benchmarked with a client on the other gigabit machine.
>> it showed 0% packet drop, when apache was not running and 4-7%, when 
>> running..
>> then i checked how it behave when i shut down apache and init a local 
>> file copy from one
>> (not system!) disk to other (not system disk either). packet drop was 
>> 5-10%, due to the higher load.
>> so i think interrupts or just the load takes the network performance, but 
>> i have no clue how to fix it.
>> is it possible that the 2000+ xp amd is just weak to serve such a 
>> traffic? (em0 traffic's maximum is 18-23MB/s)
>> i think it might be around 30MB/s without packet drop.
> 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

i have an ABIT BE7 
resting somewhere, could it improve the network performance
with a P4-2.4GHZ(533FSB)?
(i don't want Intel-AMD flame :) )

dmesg if available here:
system disks are ad4 and ad6 in raid 1, these have the files for apache 
(first i thought system disks & apache are the problem, tested on other 
disk, have
the same result)

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