Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: uswsusp history lesson [was Re: [Suspend2-devel] Re: swsusp / suspend2 reliability] | Date | Wed, 12 Jul 2006 12:09:05 +0200 |
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Hi,
On Wednesday 12 July 2006 01:00, Nigel Cunningham wrote: > Hi. > > On Wednesday 12 July 2006 08:34, Rafael J. Wysocki wrote: > > On Wednesday 12 July 2006 00:01, Nigel Cunningham wrote: > > > On Wednesday 12 July 2006 07:54, Rafael J. Wysocki wrote: > > > > On Tuesday 11 July 2006 14:45, Nigel Cunningham wrote: > > > > > Was that 10% speedup on suspend or resume, or both? With LZF, I see > > > > > approximately double the speed with both reading and writing: > > > > > > > > I was not referring to the speedup of writing and/or reading. > > > > > > > > The exercise was to measure the time needed to suspend the system and > > > > get it back in a responsive state. I measured the time elapsed between > > > > triggering the suspend and the moment at which I could switch between > > > > some applications in X without any noticeable lag due to faulting in > > > > some pages (that is a bit subjective, I must admit, but I was willing > > > > to show that bigger images make substantial difference). > > > > > > > > I tested uswsusp with compression (LZF) and two image sizes: 120 MB and > > > > (IIRC) about 220 MB on a 256 MB box. The result of the measurement for > > > > the 120 MB image has always been greater than for the 220 MB image, but > > > > the difference has never been greater than 10%. > > > > > > Ah ok. Are you sure you're getting that sort of throughput with LZF > > > though - if you're not, you might be underestimating the advantage. > > > > Certainly I don't get that kind of speedup for writing. For reading I do. > > Hmm. I would have expected it to be the other way round, since I guess you > need to do the reading synchronously - or do you read the image, then > decompress it? (I'm reading and decompressing at the same time, using > readahead to avoid waiting for pages all the time).
We're doing something like you are, but I think we're using some other option in LZF, because the resulting image size is 30-40% of the uncompressed one. That's better for encryption later on, but obviously not for speed.
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