On Sun, Nov 15, 2009 at 06:25:43PM +0100, Tobias Gruetzmacher wrote:

> And if network traffic is a problem, has anyone considered some measures
> to reduce the traffic?

That was one of the reasons we moved to squashfs/nbd.

> I have two ideas to reduce the traffic. One is for filesystem traffic:
> Implementing a persistent cache in the NBD/NFS client would free up
> network traffic for the display connections. Facilities for NFS caching
> are already present in the Linux kernel, it is "just" a matter of making
> use of them... This may even reduce boot times when all data is cached
> locally on fast storage (flash memory).

Looking forward to your patches.

> On the other hand, one could use the NX libraries to reduce the display
> traffic itself, so each client would need less bandwidth while
> operating.

This has been beaten to death in the archives, several times over.

One last time...

NX saves bandwidth at the expense of greatly increased cpu.

X simply talks over the network.

NX renders to a virtual framebuffer on the server, produces a "delta" pixmap,
compresses this, sends it over the network, client uncompresses the delta,
applies THIS to it's virtual framebuffer, and then renders on the screen.

You save greatly on bandwidth, but you're spending MUCH more in processing.  We
got this DIRECTLY from the happy-packet-dance man himself.

So, it depends on where you want to spend your money.  You can handle the
network bandwidth issues with more NIC's and better switches, relatively
cheaply.  Adding more cpu's to a box is more expensive.

However, I'm an impiricist.  What I'd like these people who keep advocating
that we drop all this silly X nonsense, and go with NX, simply IMPLEMENT IT,
send us the patches so we can include it upstream, then actually do some
measurements: network bandwidth & cpu load for 40 UNCOMPRESSED clients, and the
same for 40 NX clients on the same hardware.

Then we'd know for sure.

Scott

-- 
Scott L. Balneaves | My sources are unreliable, but their information
Systems Department | is fascinating.
Legal Aid Manitoba |     -- Ashleigh Brilliant

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