Hi. On Wed, 2009-05-27 at 00:37 +0200, Rafael J. Wysocki wrote: > Well, first, our multithreaded I/O is probably not the same thing as you think > of, because we have an option to use multiple user space threads that process > image data (compress, encrypt and feed them to the kernel). Well, I'm using multiple kernel threads, so it's probably not that different, but okay. > Now, we found that it only improves performance substantially if both > compression and encryption are used. > > As far as the numbers are concerned, I don't have the raw hdparm numbers > handy, but image writing speed with compression alone usually is in the > 60 MB/s - 100 MB/s range, sometimes more than 100 MB/s, but that really depends > on the system. If encryption is added, it drops substantially and multiple > threads allow us to restore the previous performance (not 100%, but close > enough to be worth the additional complexity IMO). Okay. That's still a significant improvement over 20 or 30 MB/s. It depends, of course, also on the compression ratio that's achieved. > Still, one should always take the total length of hibernate-resume cycle into > accout and the image writing/reading time need not be the greatest part of it. Yes, the total time is what matters. I'm focussing on the I/O speed because - especially with larger images - it tends to be the biggest portion. Regards, Nigel _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
