Messages in this thread | | | Date | Mon, 15 Aug 2016 16:33:49 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH v2 3/3] PM / hibernate: Recycle safe pages after image restoration |
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On Thu 2016-08-11 23:23:20, Rafael J. Wysocki wrote: > On Thursday, August 11, 2016 11:06:15 PM Pavel Machek wrote: > > Hi! > > > > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > > > > One of the memory bitmaps used by the hibernation image restoration > > > code is freed after the image has been loaded. > > > > > > That is not quite efficient, though, because the memory pages used > > > for building that bitmap are known to be safe (ie. they were not > > > used by the image kernel before hibernation) and the arch-specific > > > code finalizing the image restoration may need them. In that case > > > it needs to allocate those pages again via the memory management > > > subsystem, check if they are really safe again by consulting the > > > other bitmaps and so on. > > > > > > To avoid that, recycle those pages by putting them into the global > > > list of known safe pages so that they can be given to the arch code > > > right away when necessary. > > > > Ok, so you are trying to gain speed here? How much is the speedup? > > This is more about making it easier to debug than about speed, TBH. > > Avoiding bitmap operations and the mm subsystem involvement reduces > complexity and the number of places to look into in case something goes > wrong.
Well, it looked like 3/3 just added code and did not remove anything, so I fail to see how it makes code easier to follow...
Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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