Re: PATCH 2.3.26: kmalloc GFP_ZERO

yodaiken@chelm.cs.nmt.edu
Tue, 9 Nov 1999 12:55:58 -0700

On Tue, Nov 09, 1999 at 08:55:15PM +0100, Andrea Arcangeli wrote:
> On Tue, 9 Nov 1999, David S. Miller wrote:
>
> > From: Jes Sorensen <Jes.Sorensen@cern.ch>
> > Date: 09 Nov 1999 18:00:49 +0100
> >
> > now did you in fact see a 20% speedup on kernel compiles? I for
> > some reason strongly doubt that.
> >
> >I don't, it makes perfect sense since gcc is heavy on anonymous page
> >usage.
>
> Are you still talking about a cache of zeroed pages? Looks a bad idea to
> me.

The numbers say otherwise.

> It can only improve latency after some idle time. If your CPU are under
> 100% of load for a long time you'll have to spend the memset(0) time
> anyway but in another place and with an additional scheduler cost. Also

The idle task will build a cache of zeroed pages. If nothing is in the
cache, you pay the standard cost.

> the idle task will be less fast in rescheduling itself.

Why?

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