Re: [PATCH 0/6] PM / Hibernate: Memory bitmap scalability improvements

From: Pavel Machek
Date: Sat Jul 19 2014 - 06:26:41 EST


Hi!

> here is a patch set to improve the scalability of the memory
> bitmap implementation used for hibernation. The current
> implementation does not scale well to machines with several
> TB of memory. A resume on those machines may cause soft
> lockups to be reported.
>
> These patches improve the data structure by adding a radix
> tree to the linked list structure to improve random access
> performance from O(n) to O(log_b(n)), where b depends on the
> architecture (b=512 on amd64, 1024 in i386).
>
> A test on a 12TB machine showed an improvement in resume
> time from 76s with the old implementation to 2.4s with the
> radix tree and the improved swsusp_free function. See below
> for details of this test.

Ok, nice.

How did space requirements change?

In particular, do we need to reserve a bit more pages for hibernation
now?

Thanks,
Pavel
--
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