Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: shrink_all_memory tweaks (was: Re: Userland swsusp failure (mm-related)) | Date | Thu, 13 Apr 2006 15:54:30 +0200 |
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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.
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