> >>>>> "Matthew" == Matthew Wilcox <Matthew.Wilcox@genedata.com> writes:
>
> Matthew> On Tue, Nov 09, 1999 at 10:38:12AM +0100, Jes Sorensen wrote:
> >> >>>>> "Jeff" == Jeff Garzik <jgarzik@mandrakesoft.com> writes:
> >>
> Jeff> Attached is a patch against 2.3.26 which adds the GFP_ZERO flag.
> Jeff> There is a lot of code which does
> >>
> Jeff> ptr = kmalloc(size, ...); memset (ptr, 0, size);
> >> By doing this you add another `if' clause to hot path code in the
> >> memory allocator, this is IMHO not a very good idea. Let the
> >> drivers which know they need zeroed memory, clear it out
> >> themselves.
>
> Matthew> How about a zkmalloc() call which calls kmalloc, then does
> Matthew> the memset? It might lead to a small reduction in code size,
> Matthew> but it's probably pointless.
>
> Why, all it does is to provide an obfuscated macro for something which
> is not a problem. Right now some code will do kmalloc(); memset();,
> it's very clean and easy to deal with.
GFP_ZERO is not so stupid idea. It allows us to implement something like
zero-page cache. While processor has nothing to do, it can clear free
pages, and when GFP_ZERO request comes, it returns page directly without
clearing overhead.
Mikulas Patocka
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