em very slow, shared irq... on 6.3p8

[JoaoBR]

On Wednesday 27 February 2008 07:49:42 Holger Kipp wrote:
> Hello,
>
> I updated a system with 12 dc-interfaces to a new hardware
> with 14 em-interfaces. Yes, it is a firewall.
> New System is 6.2-RELEASE-p8.
>
> What I now experience between two internal networks (100MBit/s each)
> is the following:
> 1318 packets transmitted, 1317 packets received, 0% packet loss
> round-trip min/avg/max/stddev = 0.387/246.153/2441.392/324.142 ms
>
> tcpdump on the firewall shows similar delays (on the outgoing
> interface).
>
> tcpdump on the system I ping however shows very quick responses
> for incoming packages (ie usually less than a millisecond).
>
> I therefore assume that the problem is between receiving the
> irq from em<x> and getting the data from the interface on the firewall
> itself.
>
> My first option would be to activate polling on em-interfaces - but as
> I did not experience this sort of notieceable slowdown with the old
> dc-based firewall (without polling), maybe someone can shed some light
> on this strange behaviour or has other suggestions as well?



I had a setup with 4 (dlink 4port + 1 nic nfe onboard) which run extremely 
stable 6.3

I upgraded the hardware (S939 -> AM2) and used two em 2port cards, without 
polling it was certanly unusable but with polling I got very good performance

without polling normally in a day or less the machine hung, no msg, simply 
freezed

with polling it stands some days up to two weeks when it freeze again

I upgraded to 7.0 same result

check your setup with vmstat -i and if you see two nics on the same interrupt 
I guess you get the same result as I got

actual I am running one em 2port and two single port pci cards what seems to 
be stable

anyway, similare setup on Tyan MBs do not have this problem where I also have 
8 nics on one system

I also do not have this problems on S939 boards only on AM2, so I am not sure 
where the problem is exactly but seems in a certain way hardware related

You could try changing your PS unit because you might be short on power with 
lots of em cards and SATA disks




-- 

João







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