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Date: Fri, 4 Jun 2010 12:11:37 +0200 (CEST) From: Thomas Gleixner <tglx@...utronix.de> To: Peter Zijlstra <peterz@...radead.org> cc: Ingo Molnar <mingo@...e.hu>, tytso@....edu, Brian Swetland <swetland@...gle.com>, Neil Brown <neilb@...e.de>, Arve Hj?nnev?g <arve@...roid.com>, "Rafael J. Wysocki" <rjw@...k.pl>, Alan Stern <stern@...land.harvard.edu>, Felipe Balbi <felipe.balbi@...ia.com>, LKML <linux-kernel@...r.kernel.org>, Florian Mickler <florian@...kler.org>, Linux OMAP Mailing List <linux-omap@...r.kernel.org>, Linux PM <linux-pm@...ts.linux-foundation.org>, Alan Cox <alan@...rguk.ukuu.org.uk>, James Bottomley <James.Bottomley@...e.de>, Linus Torvalds <torvalds@...ux-foundation.org>, Kevin Hilman <khilman@...prootsystems.com>, "H. Peter Anvin" <hpa@...or.com>, Arjan van de Ven <arjan@...radead.org> Subject: Re: suspend blockers & Android integration On Fri, 4 Jun 2010, Peter Zijlstra wrote: > On Fri, 2010-06-04 at 11:43 +0200, Peter Zijlstra wrote: > > I still believe containment is a cgroup problem. The freeze/snapshot/resume > > container folks seem to face many of the same problems. Including the > > pending timer one I suspect. Lets solve it there. > > While talking to Thomas about this, we'd probably need a CLOCK_MONOTONIC > namespace to pull this off, so that resumed apps don't see the jump in > absolute time. > > This would also help with locating the relevant timers, since they'd be > on the related timer base. > > The only 'interesting' issue I can see here is that if you create 1000 > CLOCK_MONOTONIC namepaces, we'd need to have a tree of trees in order to > efficiently find the leftmost timer. We can do more clever than that. All CLOCK_MONOTONIC timers can live in the CLOCK_MONOTONIC rbtree, we just need proper annotation, i.e.: struct hrtimer { ktime_t expires; ...... struct list_head namespace; ktime_t base_offset; }; So expires would be on CLOCK_MONOTONIC as seen from the kernel, just the user space interfaces would take the base_offset into account. On freeze we remove the timers from the rbtree (they are easy to find via the namespace list) and on thaw we set the base_offset accordingly and insert them again. So no surprise for user space and no tree of trees to walk through. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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