packet drop with intel gigabit / marwell gigabit

[Jin Guojun [VFFS]]

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
determined.

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.

	Jin

----- 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 
> Coll
> fxp0   1500 <Link#1>      00:a0:c9:8d:79:68 13163545     0 21899372     1 
> 0
> fxp0   1500 195.38.96.64/ field                  141     - 
> 6     -     -
> em0    1500 <Link#2>      00:0e:0c:a2:ac:42 68644181     4 66793904     0 
> 0
> em0    1500 195.38.96.64/ field             211255811     - 
>      -     -
> lo0   16384 <Link#3>                        129622061     0 129622061 
> 0 0
>
> netstat -s is here:
> http://field.hu/netstat.txt
>
> ----- 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 
>> ought
>> to retry your testing at higher HZ (try 2000 or 5000):
>>
>>   echo 'kern.hz="2000"' >> /boot/loader.conf
>>
>> -- 
>> -Chuck