Messages in this thread | | | Date | Mon, 21 Jul 2014 15:06:29 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH 0/6 v2] PM / Hibernate: Memory bitmap scalability improvements |
| |
Hi!
> > > The last patch adds touching the soft lockup watchdog in > > > rtree_next_node. This is necessary because the worst case > > > performance (all bits set in the forbidden_pages_map and > > > free_pages_map) is the same as with the old implementation > > > and may still cause soft lockups. Patch 6 avoids this. > > > > Ok, so what about simpler patch? Just touch the watchdog? > > That would just cover the problem that the bitmap data structure and the > algorithm in swsusp_free do not scale well on bigmem machines.
And is it a problem? Hibernation of 12TB machine will take 6 hours if you back your swap with SSDs.
Does not scale == burns additional 60 seconds of CPU time. I think we can live with that...
...because noone sane will hibernate 12TB machine.
> > Additional 70 seconds will be lost in noise if you write 12TB of RAM > > to (even quite fast) disk. > > Sure, but you would still get the soft lockup warnings when swsusp_free > runs in the end.
Yes, that's why I propose to apply just patch 6 -- to avoid soft lockup warnings.
Best regards, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
| |