Re: [Lse-tech] Re: 10.31 second kernel compile

yodaiken
2002-03-16T20:48:31Z

On Sat, Mar 16, 2002 at 01:27:52PM -0700, Richard Gooch wrote:
> yodaiken@fsmlabs.com writes:
> > On Sat, Mar 16, 2002 at 09:05:04PM +0100, Andi Kleen wrote:
> > > That will hopefully change eventually because 2M pages are a bit help for
> > > a lot of applications that are limited by TLB thrashing, but needs some
> > > thinking on how to avoid the fragmentation trap (e.g. I'm considering
> > > to add a highmem zone again just for that and use rmap with targetted
> > > physical freeing to allocating them)
> >
> > To me, once you have a G of memory, wasting a few meg on unused
> > process memory seems no big deal.
>
> I'm not happy to throw away 2 MiB per process. My workstation has 1
> GiB of RAM, and 65 processes (and that's fairly low compared to your
> average desktop these days, because I just use olwm and don't have a
> fancy desktop or lots of windows). You want me to throw over 1/8th of
> my RAM away?!?

Why not? If you just ran vim on console you'd be more productive and
not need all those worthless processes.

At 4KB/page and 8bytes/pte a
1G process will need at least 2MB of pte alone ! Add in the 4 layers,
the software VM struct, ...

>
> And in fact, isn't it going to be more than 2 MiB wasted per process?
> For each shared object loaded, only partial pages are going to be
> used. *My* libc is less than 700 KiB, so I'd be wasting most of a page
> to map it in.

You're using a politically incorrect libc.
But sure, big pages are not always good.

> I want that 1 GiB of RAM to be used to cache most of my data. Those
> NASA 1km/pixel satellite mosaics of the world are pretty big, you know
> (21600x21600x3 per hemisphere:-).

>
> Regards,
>
> Richard....
> Permanent: rgooch@atnf.csiro.au
> Current: rgooch@ras.ucalgary.ca

--
---------------------------------------------------------
Victor Yodaiken
Finite State Machine Labs: The RTLinux Company.
www.fsmlabs.com www.rtlinux.com