On Thursday 13 April 2006 14:42, Con Kolivas wrote:
> On Wednesday 12 April 2006 03:06, Rafael J. Wysocki wrote:
> > The patch is appended.
> >
> > In shrink_all_memory() I try to free exactly as many pages as the caller
> > asks for, preferably in one shot, starting from easier targets. If slabs
> > are huge, they are most likely to have enough pages to reclaim. The
> > inactive lists are next (the zones with more inactive pages go first) etc.
> > However, since each pass potentially requires more work, the number of
> > pages to scan is decreased as the pages are reclaimed which seems to make
> > the shrinking of memory go more smoothly.
> >
> > I've been testing it on an x86_64 box for some time and it seems to behave
> > quite reasonably, eg. it usually makes the actual image size very close to
> > the value of image_size and if you set image_size to 0, it shrinks
> > everything almost totally.
>
> Great. Looks pretty good. See comments.
>
> > ---
>
> > #ifdef CONFIG_PM
> > /*
> > - * Try to free `nr_pages' of memory, system-wide. Returns the number of
> > freed - * pages.
> > + * Helper function for shrink_all_memory(). Tries to reclaim 'nr_pages'
> > pages + * from LRU lists system-wide, for given pass and priority, and
> > returns the + * number of reclaimed pages
> > + *
> > + * For pass > 3 we also try to shrink the LRU lists that contain a few
> > pages + */
> > +unsigned long shrink_all_zones(unsigned long nr_pages, int pass, int prio,
> > + struct scan_control *sc)
>
> I like how this moves all suspend vm functions out of the generic functions
> even more than I managed to.
>
> > + int swappiness = vm_swappiness, pass;
> > + struct reclaim_state reclaim_state;
> > + struct zone *zone;
> > + struct scan_control sc = {
> > + .gfp_mask = GFP_KERNEL,
> > + .may_swap = 1,
> > + .swap_cluster_max = nr_pages,
> > + .may_writepage = 1,
> > };
>
> This is not quite right at maintaining the original semantics I was proposing.
> Since you are iterating over all priorities, setting may_swap means you will
> reclaim mapped ram on the earlier passes once priority gets low enough.
No, I won't, because I don't update zone->prev_priority which is necessary
to trigger this. Unless of course zone->prev_priority is already low enough ...
> Setting vm_swappiness temporarily to 100 is unncecessary. You should set
> may_swap to 0 and set it to 1 on passes 3+.
... which can be dealt with by setting may_swap like you're saying.
I'll make this change and repost as an RFC in a separate thread.
> Otherwise, looks good, thanks!
Thanks a lot for the comments.
Greetings,
Rafael
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