Messages in this thread | | | Date | Wed, 31 Oct 2012 18:31:54 +0100 | From | Pavel Machek <> | Subject | Re: [PATCH] add some drop_caches documentation and info messsge |
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On Mon 2012-10-29 10:58:19, Borislav Petkov wrote: > On Mon, Oct 29, 2012 at 09:59:59AM +0100, Jiri Kosina wrote: > > You might or might not want to do that. Dropping caches around suspend > > makes the hibernation process itself faster, but the realtime response > > of the applications afterwards is worse, as everything touched by user > > has to be paged in again.
Also note that page-in is slower than reading hibernation image, because it is not compressed, and involves seeking.
> Right, do you know of a real use-case where people hibernate, then > resume and still care about applications response time right afterwards?
Hmm? When I resume from hibernate, I want to use my machine. *Everyone* cares about resume time afterwards. You move your mouse, and you don't want to wait for X to be paged-in.
> Besides, once everything is swapped back in, perf. is back to normal, > i.e. like before suspending.
Kernel will not normally swap anything in automatically. Some people do swapoff -a; swapon -a to work around that. (And yes, maybe some automatic-swap-in-when-there's-plenty-of-RAM would be useful.). Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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