Re: [linux-audio-dev] It's time to vote (n. 1)

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Subject: Re: [linux-audio-dev] It's time to vote (n. 1)
From: Jörn Nettingsmeier (nettings_AT_folkwang-hochschule.de)
Date: Thu May 24 2001 - 13:56:13 EEST


Paul Davis wrote:
>
> >> I'm just wondering, since I'm getting a .7 ms roundtrip time when
> >> pinging my other Linux system here, which is connected to this one
> >> by 100 Mbps ethernet through a 100 Mbps switch. Is that number
> >> for real? Because it seems almost too good.
> >
> >I get 150-250usec (yes, microseconds) roundtrip through 100mbps switch.
>
> is this on a previously quiescent connection (TCP or UDP) ? my
> impression is that once things get rolling round trip times are pretty
> good, but that moving a packet or two when there's been no traffic in
> a few msecs produces much worse numbers. my impression may be wrong.
>
> i'd also like to point out that the lowest value mentioned above is
> more than 10% of the total time available to process a 64 frame chunk
> of audio at 48kHz :)
>
> --p

here is a typical ping on my local unswitched 100mb/s cat5 network:

nettings_AT_kleineronkel:~ > ping spunk
PING spunk.villakunterbunt.netz (192.168.200.200): 56 data bytes
64 bytes from 192.168.200.200: icmp_seq=0 ttl=255 time=0.298 ms
64 bytes from 192.168.200.200: icmp_seq=1 ttl=255 time=0.246 ms
64 bytes from 192.168.200.200: icmp_seq=2 ttl=255 time=0.243 ms
64 bytes from 192.168.200.200: icmp_seq=3 ttl=255 time=0.237 ms
64 bytes from 192.168.200.200: icmp_seq=4 ttl=255 time=0.253 ms
64 bytes from 192.168.200.200: icmp_seq=5 ttl=255 time=0.236 ms
64 bytes from 192.168.200.200: icmp_seq=6 ttl=255 time=0.232 ms
64 bytes from 192.168.200.200: icmp_seq=7 ttl=255 time=0.243 ms
--- spunk.villakunterbunt.netz ping statistics ---
8 packets transmitted, 8 packets received, 0% packet loss
round-trip min/avg/max = 0.232/0.248/0.298 ms

if the first (longer) round-trip time is a measure for the case that
paul mentioned, there should be no problem with newly initiated
connections.
what is the chunk size that we will typically expect for audio
connections ?
then we could check with ping -s for slightly more realistic
figures..

-- 
Jörn Nettingsmeier     
home://Kurfürstenstr.49.45138.Essen.Germany      
phone://+49.201.491621
http://icem-www.folkwang-hochschule.de/~nettings/
http://www.linuxdj.com/audio/lad/


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