Re: [PATCH] add some drop_caches documentation and info messsge
From: Pavel Machek <hidden>
Date: 2012-10-31 17:31:58
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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:quoted
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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>