Re: isdn performance problem in 2.1[19]-[22]

Henner Eisen (eis@baty.hanse.de)
25 Sep 1998 22:46:13 +0200


Hi,

Richard Schiffelers <ricrjhl@xs4all.nl> writes:

>
> At 11:58 24-9-98 +0200 Markus Brischke wrote:
> >I noticed that the throughput of my isdn is really bad with 2.1
> >beginning with 1 kb/s and 5 sec later 400 b/s. I am using a teles hisax 16.3
> >Card. First i thought that it could be a problem of my provider
> >, so i testet the same things with my stable 2.0.33 kernel and got
> >ca. 8kb/s. I am using predictor compression. My pppd 2.3pl3.
> >
> >I tested this on different days at different times.
> >
> >Does anybody notice same problems?
>
> Yep, same problems. Also using Teles card. I noticed the slowdown in speed
> when i started to run 2.1.122 (didn't run any earlyer 2.1 version together
> with ISDN). I decided to check out what was going on with IPTraf. It showed
> that on de ippp0 interface around 50% of all packets had a wrong checksum
> (and wich are therefore resend). I then switched back to 2.0.35 and again
> checked with IPTraf. No problem and no bad packets. So it seems 2.1 is not
> 100%. Ok, that probably why is it experimental *8^>
>
> >Does anybody have a hint how to fix it.

Maybe this could also indicate a low level driver problem. Maybe upgrading
to a recent snapshot from the i4l CVS tree might help against driver problem.

However, I've also sometimes observed such problems (not reproducible,
but with current i4l cvs versions). Could those of you observing
performence problems with isdn on 2.1.x please try the following
patch? It's against the current cvs version, but should also apply
against stock 2.1.122 kernel.

Henner

--- 2.1.122-i4ldev/drivers/isdn/isdn_net.c Mon Sep 7 23:23:03 1998
+++ 2.1.122-ix25/drivers/isdn/isdn_net.c Fri Sep 25 21:47:41 1998
@@ -1225,12 +1226,14 @@
if (ret == len) {
lp->transcount += len;
clear_bit(0, (void *) &(ndev->tbusy));
+ mark_bh(NET_BH);
return 0;
}
if (ret < 0) {
dev_kfree_skb(skb);
lp->stats.tx_errors++;
clear_bit(0, (void *) &(ndev->tbusy));
+ mark_bh(NET_BH);
return 0;
}
return 1;

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