Re: Populating multiple ptes at fault time

[Jeremy Fitzhardinge <jeremy@goop.org>]

Rik van Riel wrote:
> On Wed, 17 Sep 2008 10:47:30 -0700
> Jeremy Fitzhardinge <jeremy@goop.org> wrote:
>
>   
>> Minor faults are easier; if the page already exists in memory, we should
>> just create mappings to it.  If neighbouring pages are also already
>> present, then we can can cheaply create mappings for them too.
>>     
>
> This is especially true for mmaped files, where we do not have to
> allocate anything to create the mapping.
>   

Yes, that was the case I particularly had in mind.

> Populating multiple PTEs at a time is questionable for anonymous
> memory, where we'd have to allocate extra pages.
>   

It might be worthwhile if the memory access pattern to anonymous memory
is linear.  I agree that speculatively allocating pages on a random
access region would be a bad idea.

    J