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Re: Process priorities

On Wednesday, September 18, 2002, at 07:57 AM, Tor Hildrum wrote:

<email@hidden> wrote:

This issue is of particular
concern to
me because I use FreeBSD so frequently...and most of the processes on
that
platform FEEL like they execute more quickly, dramatically more
quickly--doing so on hardware that shouldn't be (isn't) faster.

If you use "top -d" (or "top -ud"), Darwin's top won't consume that many
cycles either (it's still slightly more than under the other OS'es
though). It's the gathering of memory statistics that consumes so much
time. On darwin-development, Apple engineers also always say this is
because traversing the mach memory maps is a lot of work. Maybe the
memory mapping under FreeBSD (and Linux) is in fact much simpler than
under mach... Anyway, the source of all things involved is available, so
nothing prevents you from finding out what the real cause is (except for
time, probably :)

I'm just guessing, but could this be because of kernel-architecture?
Micro vs Monolithic?

They used to say, back in the days, that monolithic kernels where faster.

The Darwin kernel is monolithic, despite the presence of Mach. Mach 3.x was designed to support microkernel architectures, but that isn't a requisite of its use. In Darwin, the BSD, IOKit, and Mach pieces are pretty tightly bound.

The performance issue is as stated: there's a lot of effort involved to overcomeXXXXXdeal with the Mach VM architecture for statistics purposes.

Regards,

Justin

--
Justin C. Walker, Curmudgeon-At-Large *
Institute for General Semantics | Men are from Earth.
| Women are from Earth.
| Deal with it.
*--------------------------------------*-------------------------------*
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References: 
 >Re: Process priorities (From: Tor Hildrum <email@hidden>)



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