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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 16:10:27 +0200	[thread overview]
Message-ID: <20140721141027.GA16042@amd.pavel.ucw.cz> (raw)
In-Reply-To: <20140721133800.GM30979@8bytes.org>

Hi!

> > > 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...
> 
> Problem is that these 76s are burned every time, whether you just use
> 500MB or the full 12TB of the machine.

On 12TB machine, how much memory is used after boot finishes? I
suspect it is not 500MB.

> Next problem is that the bitmaps are allocated (and need to be freed)
> without even being sure that a resume will happen.

Could we fix that instead? Allocating bitmaps before we see
hibernation signature is a bug.

[How long does 12TB machine boot?]

> > ...because noone sane will hibernate 12TB machine.
> 
> And Linux is only made for sane people? Thats pretty new to me ;-)

Yeah, but please don't optimize for insane people :-).

> > Yes, that's why I propose to apply just patch 6 -- to avoid soft
> > lockup warnings.
> 
> Only patch 6 would wrap the problem with the soft lockups, but the other
> patches actually improve the resume and boot situation on those
> machines.

Yeah. Provide timings for 12TB machine suspending/resuming and we may
talk about it.

#6 is bugfix. We should take it. Rest is performance improvement for
insane config. I don't think we should take it.

								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 14:10 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
2014-07-21 13:38       ` Joerg Roedel
2014-07-21 14:10         ` Pavel Machek [this message]
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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