[bittorrent] Introductory/endgame algorithms

Olaf van der Spek olafvdspek at gmail.com
Fri Sep 30 07:01:07 EDT 2005


On 9/30/05, Justin Cormack <justin at street-vision.com> wrote:
>
> On 30 Sep 2005, at 08:27, Olaf van der Spek wrote:
> >
> >> Wrong. If your buffer is page-aligned and you're doing I/O to
> >> page-aligned portions of a file, Linux will do a copy but by
> >> modifying
> >> the page table.
> >>
> >
> > Doesn't that also require not using the buffer for anything else
> > (afterwards)?
> > Because if you write to it, Linux will have to do the copy after all.
>
> Linux doesnt do this. I think FreeBSD does, but the page table
> mangling was considered
> not worthwhile.

Then what does Linux do?
Remove the page from the global page cache and make it local to your app?



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