packet drop with intel gigabit / marwell gigabit
Jin Guojun [VFFS]
g_jin at lbl.gov
Sun Mar 19 00:48:01 UTC 2006
It is still not clear how you did measurement.
Did FTP show such % drop? or Did you measure it by other tools?
How did you measured incoming traffic?
http://field.hu/netstat.txt shows 0 tcp packet drop.
Anyway, the first thing first is to have CPU utilization when you see packet drop.
This can be get from running "top" or "vmstat 1". As well as run
netstat -i -p tcp | grep -i drop
If CPU utilization is approaching 100%, either the traffic is no 2 MBps,
or some process is taking CPU time. For this reason, "top" is a better
tool to use. At this point, if you run netstat command multiple times,
you would see drop counter increasing.
Once you find out what process takes CPU time, then further tuning can be
If CPU utilization is well below 70-80%, then you need to use tcpdump and
tcptrace to visualize what cause packet drop, then perform a solution.
----- Original Message -----
From: "OxY" <oxy at field.hu>
To: "Chuck Swiger" <cswiger at mac.com>
Cc: <freebsd-performance at freebsd.org>
Sent: Saturday, March 18, 2006 2:23 PM
Subject: Re: packet drop with intel gigabit / marwell gigabit
> currently i use HZ=2000
> here's the output of netstat -i, -s, and vmstat -i :
> (currently i am uploading on the gigabit with ftp, 3 threads)
> Field root# vmstat -i
> interrupt total rate
> irq0: clk 27503959 1993
> irq1: atkbd0 1 0
> irq3: fxp0 2 0
> irq7: 146 0
> stray irq7 146 0
> irq8: rtc 1765569 127
> irq10: atapci1 2807786 203
> irq11: atapci0 475039 34
> irq13: npx0 1 0
> irq14: ata0 99 0
> Total 32552748 2359
> Field root# netstat -i
> Name Mtu Network Address Ipkts Ierrs Opkts Oerrs
> fxp0 1500 <Link#1> 00:a0:c9:8d:79:68 13163545 0 21899372 1
> fxp0 1500 184.108.40.206/ field 141 -
> 6 - -
> em0 1500 <Link#2> 00:0e:0c:a2:ac:42 68644181 4 66793904 0
> em0 1500 220.127.116.11/ field 211255811 -
> - -
> lo0 16384 <Link#3> 129622061 0 129622061
> 0 0
> netstat -s is here:
> ----- Original Message -----
> From: "Chuck Swiger" <cswiger at mac.com>
> To: "OxY" <oxy at field.hu>
> Cc: <freebsd-performance at freebsd.org>
> Sent: Saturday, March 18, 2006 1:37 PM
> Subject: Re: packet drop with intel gigabit / marwell gigabit
>> OxY wrote:
>>> yeah, i googled these settings, but i put them back to default then!
>>> i measured iperf performance, and it showed that the packet drop is
>>> depending on the system load..
>> If you are using the normal interrupt-driven configuration, you should
>> look at
>> netstat -i, -s, and vmstat -i. If you're turning on device polling, you
>> to retry your testing at higher HZ (try 2000 or 5000):
>> echo 'kern.hz="2000"' >> /boot/loader.conf
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