NE2k driver issue

NE2k driver issue

[Samium Gromoff]

	I`ve experienced a very strange relationship between
ISA sb card generated interrupts and network NIC perfomance.

	The situation was the next: i`ve performed a data transfer from
a remote samba share to the local box thru a 10Mbit ISA NIC.
What has been varying was the interrupt load of the sound card.
With esd started the sound card generated 500-600 interrupts/second,
with no esd, it didnt generated interrupts.

	Theoretically the sbcard interrupts should make the NIC starve
and reduce the NIC performance. But the situation i`ve experienced
was weird as hell.

	With esd started the samba transfer maxes out at 400kb/s.
	With esd stopped it immediately drops down to 30-35 kb/s.

This is also well reflected by the NIC interrupt rate cutting down
by 90% with esd stopped.

	Info: linux-2.4.17-rmap12e, NE2k ISA NIC, SB16 Vibra ISA

regards, Samium Gromoff

Re: NE2k driver issue

[Andreas Dilger]

On Feb 19, 2002  16:18 +0300, Samium Gromoff wrote:
> With esd started the sound card generated 500-600 interrupts/second,
> with no esd, it didnt generated interrupts.

This is a known problem with esd - it plays "the sound of silence" all
the time.  This means it is generating interrupts even when you aren't
listening to anything.

Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://www-mddsp.enel.ucalgary.ca/People/adilger/

Re: NE2k driver issue

[Andrew Morton]

Andreas Dilger wrote:
> 
> On Feb 19, 2002  16:18 +0300, Samium Gromoff wrote:
> > With esd started the sound card generated 500-600 interrupts/second,
> > with no esd, it didnt generated interrupts.
> 
> This is a known problem with esd - it plays "the sound of silence" all
> the time.  This means it is generating interrupts even when you aren't
> listening to anything.
> 

But the odd thing is that the soundcard interrupts tentupled the
samba throughput.  Which sounds like a driver-handoff-to-ksoftirqd
problem. 

-

Re: NE2k driver issue

[Alan Cox]

> > the time.  This means it is generating interrupts even when you aren't
> > listening to anything.
> 
> But the odd thing is that the soundcard interrupts tentupled the
> samba throughput.  Which sounds like a driver-handoff-to-ksoftirqd
> problem. 

Or an IRQ routing bug

Re: NE2k driver issue

[Samium Gromoff]

"  Alan Cox wrote:"
> 
> > > the time.  This means it is generating interrupts even when you aren't
> > > listening to anything.
> > 
> > But the odd thing is that the soundcard interrupts tentupled the
> > samba throughput.  Which sounds like a driver-handoff-to-ksoftirqd
> > problem. 
> 
> Or an IRQ routing bug
> 
   Okay guys, new data on this issue.
	the kernel 2.4.17 which i used so far had this issue - ie the transfer rate drop
400k -> 20-30k without esd.
	i recently switched to 2.4.19-pre3 and the behaviour reverted:
now it drops 300k -> 50k due to esd active.

	i think both behaviours are broken, cause the 2.4.17 case clearly shows that
ne2k perfectly runs at full speed with _active_ esd.

	ie summarizing we have:
		2.4.17:		esd -> 20k bumps to 400k
		2.4.19p3:	esd -> 300k drops to 50k

regards, Samium Gromoff