Hi -
> From: [EMAIL PROTECTED]
> I use netpipes instead of rsh, but either way the network shouldn't be
I gave netpipes a try - worked "ok" but I couldn't find a way
to pass parameters thru to the remote process. Easy to set up
a shell script of course.
> much of a bottleneck given that you're still only talking 4-6 fps at
True, a 100Mb network isn't a bottleneck for a single encoding
session and if not a lot else is going on at the same time.
However, 'rsh/rshd' does consume a lot of cpu cycles in addition to
the overhead of the IP/TCP work the kernel is doing. Start 'top'
in another window and watch 'rshd' sometime.
Ssh/sshd is even higher overhead because it's encrypting and
decrypting the data.
I saw a dramatic increase in the encoding rate (did I post the
numbers? Thought I did...) when using netpipes vs. rsh/ssh on a
single cpu system (a notebook).
On a multi cpu system there's not much, if any, difference between
rsh/ssh/netpipes because the additional cpu(s) can be moving the
data over the network at the same time the programs are filtering,
and encoding.
> The trick is to balance the load, or else one of the CPUs gets wasted.
True. One way to enhance the value of that trick is to use dual
cpu systems (quad cpu systems are nice but the only ones I have access
to are at work and sneakernetting 20GB of data is a nuisance ;))
Cheers,
Steven Schultz
> the cpu requirements drop off considerably. And obviously you can't
> send data too many times across the same network to multiple machines
> at once, or it will become the bottleneck eventually.
The overhead of receiving and sending the data multiple times will
seriously erode the benefits of the distributed processing. With
Gigabit ethernet (and 8 port 'consumer level' GigE switches are down
to $200) it's possible to get more encoding going over the network
but the amount of cpu time used by the kernel and rsh/ssh will grow
as the mount of data increases.
A friend of mine found that a dual AthlonMP system was a very
costeffective way of increasing the encoding speed. When my dual
800P3 system finally breaks or I get tired of it I'll just swap in
a dual AthlonMP setup.
Cheers,
Steven Schultz
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