Messages in this thread | | | Date | Thu, 7 Jun 2001 16:30:08 -0300 (BRT) | From | Marcelo Tosatti <> | Subject | Re: Background scanning change on 2.4.6-pre1 |
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On Thu, 7 Jun 2001, Linus Torvalds wrote:
> > Forgot one comment.. > > > > This is going to make all pages have age 0 on an idle system after some > > > time (the old code from Rik which has been replaced by this code tried to > > > avoid that) > > There's another reason why I think the patch may be ok even without any > added logic: not only does it simplify the code and remove a illogical > heuristic, but there is nothing that really says that "age 0" is > necessarily very bad. > > We should strive to keep the active/inactive lists in LRU order anyway, so > the ordering does tell you something about how recent (and thus how > important) the page is. Also, it's certainly MUCH preferable to let pages > age down to zero, than to let pages retain a maximum age over a long time, > like the old code used to do. > > If, after long periods of inactivity, we start needing fresh pages again, > it's probably actually an _advantage_ to give the new pages a higher > relative importance. Caches tend to lose their usefulness over time, and > if the old cached pages are really relevant, then the new spurt of usage > will obviously mark them young again. > > And if, after the idle time, the behaviour is different, the old pages > have appropriately been aged down and won't stand in the way of a new > cache footprint. > > Do you actually have regular usage that shows the age-down to be a bad > thing?
Fill the active list of cache and wait for a while to get the inactive list full.
When that happens and pressure begins, refill_inactive_scan() from try_to_free_pages() will not be called because the inactive list is full (the kernel "thinks" we dont have an inactive shortage). Well, not sure if this is a bad thing in the end.
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