Re: Increase page fault rate by prezeroing V1 [1/3]: Introduce__GFP_ZERO

[Christoph Lameter]

On Tue, 21 Dec 2004, Andi Kleen wrote:

> Christoph Lameter <clameter@xxxxxxx> writes:
> > @@ -0,0 +1,52 @@
> > +/*
> > + * Zero a page.
> > + * rdi	page
> > + */
> > +	.globl zero_page
> > +	.p2align 4
> > +zero_page:
> > +	xorl   %eax,%eax
> > +	movl   $4096/64,%ecx
> > +	shl	%ecx, %esi
>
> Surely must be shl %esi,%ecx

Ahh. Thanks.

> But for the one instruction it seems overkill to me to have a new
> function. How about you just extend clear_page with the order argument?

We can just

#define clear_page(__p) zero_page(__p, 0)

and remove clear_page?

>
> BTW I think Andrea has been playing with prezeroing on x86 and
> he found no benefit at all. So it's doubtful it makes any sense
> on x86/x86-64.

Andrea's approach was:

1. Zero hot pages
2. Zero single pages

which simply results in shifting the processing time somewhere else.
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