Re: 2.4.23aa2 (bugfixes and important VM improvements for the highend)

[Andrew Morton]

Andrea Arcangeli <andrea@xxxxxxx> wrote:
>
> On Fri, Mar 05, 2004 at 12:41:19PM -0800, Andrew Morton wrote:
> > Andrea Arcangeli <andrea@xxxxxxx> wrote:
> > >
> > > > > The main thing you didn't mention is the overhead in the per-cpu data
> > >  > > structures, that alone generates an overhead of several dozen mbytes
> > >  > > only in the page allocator, without accounting the slab caches,
> > >  > > pagetable caches etc.. putting an high limit to the per-cpu caches
> > >  > > should make a 32-way 32G work fine with 3:1 too though. 8-way is
> > >  > > fine with 32G currently.
> > >  > 
> > >  > Humpf. Do you have a hard figure on how much it actually is per cpu?
> > > 
> > >  not a definitive one, but it's sure more than 2m per cpu, could be 3m
> > >  per cpu.
> > 
> > It'll average out to 68 pages per cpu.  (4 in ZONE_DMA, 64 in ZONE_NORMAL).
> 
> 3m per cpu with all 3m in zone normal.

In the page allocator?  How did you arrive at this figure?
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