Re: 2.4.8-pre1 and dbench -20% throughput

Linus Torvalds
2001-07-28T20:26:48Z

On Sat, 28 Jul 2001, Daniel Phillips wrote:
>
> Here is what I think is happening on a typical burst of small, non-page
> aligned reads:
>
> - Page is read the 1st time: age = 2, inactive
> - Page is read the second time: age = 5, active
> - Two more reads immediately on the same page: age = 11

No.

We only mark the page referenced when we read it, we don't actually
increment the age.

The _aging_ is only done by the actual scanning routines.

At least that's how it should work. A quick grep for who does
"age_page_up()" shows that it is only done by refill_inactive_scan().
(page_launder() doesn't need to do it, because it already knows the age is
zero on the inactive list, so it just sets the age).

Maybe the problem is that use-once works on accesses, not on ages?

Linus