Re: bigphysarea support in 2.2.19 and 2.4.0 kernels

Albert D. Cahalan
2000-12-24T09:30:10Z

Eric W. Biederman writes:

> If you are doing a real time task you don't want to very close
> to your performance envelope. If you are hitting the performance
> envelope any small hiccup will cause you to miss your deadline,
> and close to your performance envelope hiccups are virtually certain.
>
> Pushing the machine just 5% slower should get everything going
> with multiple pages, and you wouldn't be pushing the performance
> envelope so your machine can compensate for the occasional hiccup.
>
>> The data stream is fat and relentless.
>
> So you add another node if your current nodes can't handle the load
> without using giant physical areas of memory. Attempt to redesign
> the operating system. Much more cost effective.

Nodes can be wicked expensive. :-)

Pushing the performance envelope is important when you want to
sell lots of systems. Radar is a similar computational task,
with the added need to reduce space and weight requirements.
It's not OK to be 5% more expensive, bulky, and heavy.

Also the Airplane Principal: more nodes means more big failures.