Re: DP performance

[Danial Thom <danial_thom@xxxxxxxxx>]

--- Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>
wrote:

>     Well, if you think they're so provably
> wrong you are welcome to
>     put forth an actual technical argument to
> disprove them, rather then 
>     throw out derogatory comments which contain
> no data value whatsoever.
>     I've done my best to explain the technical
> issues to you, but frankly
>     you have not answered with a single
> technical argument or explanation
>     of your own.  If you are expecting
> acolades, you are aren't going to
>     get them from any of us.

The only accolades I need are in the form of $$.
I'm hoping to find a suitable OS for the next
generation of product, so that's my only goal.

Fire X number of packets at a system bridging
packets and the machine will go into livelock
before it starts flow controlling, and as you
increase the PPS volume you'll see buckets of
packets dropped. The value of 'X' is different on
every machine of course, and somewhat linear on
the same machine with different CPUs. You can
tune it until the cows come home, but there's
nothing elegant about it. If you do in fact enter
a flow controlled state, buckets of packets are
lost in the process, by both the sending and
receiving machines. Flow control merely shifts
the losses; its not a solution, its a symptom
that maans your machine isn't fast enough to
handle the required load.

You realize of course that by the time you have a
ring breach and flow control is issued and you
can catch up you've lost 1000s of packets at gigE
speeds, right?

Its hard to disprove something that is mindless,
such as your claim that modern processors cannot
be overrun. Its so patently ridiculous that its
like proving that sand is squishy. It takes
*some* amount of CPU to process a packet.
Certainly over the years that amount has become
less and less. But I really don't get your point,
or how it related to making MP faster then UP.
Are you saying that since processors are fast
enough to handle huge network loads that there is
no reason to make the OS better? So if you're not
running 10gigE then there's no reason to use
multiple processors?

DT


		
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