Re: 2.1.91 swap performance: jerky.

Itai Nahshon (nahshon@actcom.co.il)
Sat, 28 Mar 1998 05:48:37 +0300

Linus Torvalds wrote:
>
> On Sat, 28 Mar 1998, Itai Nahshon wrote:
> >
> > The idea sounds right, I have questions regarding limitation on
> > current implementation:
> > 1. If something is swapped out but the pages that it occupied
> > never used later, will it have to be paged-in from disk or can
> > the copy in memory be reused without any farter io?
>
> If the page is never used again, it will never be paged in: an exit of the
> process will just free up the page on disk, and a "fork()" will duplicate
> the pointer to the disk rather than page it in in order to duplicate it.

I did not phrase my question right...
Suppose a page was swapped out, but the physical memory that it occupied
was not used for something else. Now the process page-faults in that
address. Can the page be reclaimed from memory (the data is still
in the main memory?) or do we need to page-in from disk?

Thanks,
Itai

-- 
Itai Nahshon   nahshon@actcom.co.il
        Also   nahshon@vnet.ibm.com


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