Re: MM deadlock [was: Re: arca-vm-8...]

Zlatko Calusic
1999-01-13T06:52:27Z

Rik van Riel <riel@humbolt.geo.uu.nl> writes:

> On 12 Jan 1999, Zlatko Calusic wrote:
>
> > After number of async pages gets bigger than
> > pager_daemon.swap_cluster (= SWAP_CLUSTER_MAX), swapin readahead
> > becomes synchronous, and that hurts performance. It is better to
> > skip readahead in such situations, and that is also more fair to
> > swapout. Andrea came to exactly the same conclusion, independent
> > of me (on the same day :)).
>
> IIRC this facility was in the original swapin readahead
> implementation. That only leaves the question who removed
> it and why :))
>

*I* did, because original test was too complicated and nobody
understood what was it actual purpose.

Beside that, when MM code changed recently, nr_free_pages started
hovering at lower values, and that was killing readahead at most cases
(with old test in place), thus producing terrible results, especially
when you had more than one thrashing task.

--
Zlatko