Linux-Hams archive - May 1998: Re: scc module buffers only up to 8 packets, with quick hack..

Re: scc module buffers only up to 8 packets, with quick hack..

Richard Adams (andxt.jsnfavw@us.edu.pl)
Thu, 30 Apr 1998 21:00:00 +0000 (GMT)


According to Arjan Filius: While burning my CPU.
>
> Hello Joerg,
>
> About the scc linux kernel driver:
>
> While testing whith the ping preload option, i found out that the scc
> driver (kernel 2.1.98 and prior) bufers only up to 8 packets (arbitrary
> size). ex: ping -l 20 -s 8 -i 60 -c 22 <my-ax25-hostname>, and then only
> the last 7 a 8 pings returned

My 2 cents worth.

When i do ping -c8 -l7 -i5 -s472 pi1goe
i get via my 9k6 link 100% link quality.
Could it be someting else than maxqueue ??
I thought that linux had a standard ping size of 24 bytes, ?

At least i have never come across any other problem other than sending too
many packets and causing the tramsmitter to key longer than the defined
maxkey time, or was it something else.?
Other than that i dont see your point.!!

And doing:

/usr/src/linux$ ping -c9 -l8 -i5 -s123 pi1goe
PING pi1goe.ampr.org (44.137.28.27): 123 data bytes
131 bytes from 44.137.28.27: icmp_seq=0 ttl=64 time=1849.0 ms
131 bytes from 44.137.28.27: icmp_seq=1 ttl=64 time=1986.2 ms
131 bytes from 44.137.28.27: icmp_seq=2 ttl=64 time=2124.3 ms
131 bytes from 44.137.28.27: icmp_seq=3 ttl=64 time=2262.5 ms
131 bytes from 44.137.28.27: icmp_seq=4 ttl=64 time=2399.8 ms
131 bytes from 44.137.28.27: icmp_seq=5 ttl=64 time=2538.0 ms
131 bytes from 44.137.28.27: icmp_seq=6 ttl=64 time=2676.0 ms
131 bytes from 44.137.28.27: icmp_seq=7 ttl=64 time=2814.2 ms
131 bytes from 44.137.28.27: icmp_seq=8 ttl=64 time=2952.3 ms

--- pi1goe.ampr.org ping statistics ---
9 packets transmitted, 9 packets received, 0% packet loss
round-trip min/avg/max = 1849.0/2400.2/2952.3 ms

>
> I sniffed in the source and found:
> /usr/src/linux-2.1.98/drivers/net/hamradio/scc.c,132:
> #define MAXQUEUE 8 /* number of buffers we queue ourself */
>
> i increased this constand to 80, and no 'buffer overflows' occur. (ping
> works now ok)

I am now totaly confused.??? Joreg!.

>
> Greatings,
>
> Arjan Filius
> Email: lqmk@tn.cl
> --------------------------------------------------------------
> Argh! All right, so how am I supposed to work with Linux when
> everything's already been done?! Can't these people leave some
> broken MSDOS like parts so there's problems left to solve!?....
>

-- 
Regards Richard.
dcvuy.ogbxy@rele.tunk.net