RE: [2.4.17/18pre] VM and swap - it's really unusable

Gonzalez, Inaky
2002-01-08T21:46:16Z

> And while I'm enumerating differences, the preemptable kernel
> (in this
> incarnation) has a slight per-spinlock cost, while the
> non-preemptable kernel
> has the fixed cost of checking for rescheduling, at intervals
> throughout all
> 'interesting' kernel code, essentially all long-running
> loops.

For a general case, that cost is leveraged by the improvement in scheduling,
by filling out the IO channels better, and thus, using most resources more
efficiently. I did some dirty tests that showed that the preemptible kernel
performed more or less one second better than the normal one when unzipping
and compiling a kernel [dirty general case]. The std deviation is around the
time difference, so we can quite conclude the impact is zero -- asides from
the improvement in responsiveness].

Please see my message to the mailing list at
http://www.geocrawler.com/archives/3/14905/2001/11/0/7074067/ [the excel
spreadsheet is available at request].

Iñaky Pérez González -- (503) 677 6807
I do not speak for Intel Corp, opinions are my own.