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From: Pavel Machek <pavel@ucw.cz>
To: Joerg Roedel <joro@8bytes.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Len Brown <len.brown@intel.com>,
	linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/6 v2] PM / Hibernate: Memory bitmap scalability improvements
Date: Mon, 21 Jul 2014 15:06:29 +0200	[thread overview]
Message-ID: <20140721130629.GA15122@amd.pavel.ucw.cz> (raw)
In-Reply-To: <20140721123613.GL30979@8bytes.org>

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

  reply	other threads:[~2014-07-21 13:06 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-21 10:26 [PATCH 0/6 v2] PM / Hibernate: Memory bitmap scalability improvements Joerg Roedel
2014-07-21 10:26 ` [PATCH 1/6] PM / Hibernate: Create a Radix-Tree to store memory bitmap Joerg Roedel
2014-07-21 22:36   ` Joerg Roedel
2014-07-21 23:05     ` Pavel Machek
2014-07-21 10:26 ` [PATCH 2/6] PM / Hibernate: Add memory_rtree_find_bit function Joerg Roedel
2014-07-21 10:26 ` [PATCH 3/6] PM / Hibernate: Implement position keeping in radix tree Joerg Roedel
2014-07-21 10:27 ` [PATCH 4/6] PM / Hibernate: Iterate over set bits instead of PFNs in swsusp_free() Joerg Roedel
2014-07-21 10:27 ` [PATCH 5/6] PM / Hibernate: Remove the old memory-bitmap implementation Joerg Roedel
2014-07-21 10:27 ` [PATCH 6/6] PM / Hibernate: Touch Soft Lockup Watchdog in rtree_next_node Joerg Roedel
2014-07-21 12:00 ` [PATCH 0/6 v2] PM / Hibernate: Memory bitmap scalability improvements Pavel Machek
2014-07-21 12:36   ` Joerg Roedel
2014-07-21 13:06     ` Pavel Machek [this message]
2014-07-21 13:38       ` Joerg Roedel
2014-07-21 14:10         ` Pavel Machek
2014-07-21 16:03           ` Joerg Roedel
2014-07-21 23:05             ` Pavel Machek
2014-07-22  0:41               ` Rafael J. Wysocki
2014-07-22 10:34                 ` Joerg Roedel
2014-07-22 10:55                   ` Pavel Machek
2014-07-22 12:24                     ` Joerg Roedel
2014-07-22 10:58                   ` Pavel Machek
2014-07-22 12:10                     ` Joerg Roedel
2014-07-23 10:57                       ` Pavel Machek
2014-07-28 13:59                   ` Borislav Petkov
2014-07-29 21:22                     ` Rafael J. Wysocki

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