Re: swsusp performance problems in 2.6.15-rc3-mm1

[Pavel Machek]

Hi!

> > > Let me explain what I have in mind.
> > > 
> > > For starters, please observe that the addresses we use are page-aligned,
> > > so the least significant bit is always zero.  Thus it can be used as a marker.
> > > 
> > > Now before we save the image we can mark blank pages by setting
> > > the least significant bit of .orig_address to 1 in the coresponding PBEs.
> > > We save the "marked" .orig_address values to the image.
> > 
> > Well, nice optimalization, but how many pages are actually full of
> > zeros?
> 
> According to the results I have obtained, there are about 1000 such
> pages in the image on my box, for total image sizes between 28000
> and 80000 pages (ie above 28000 of pages in the image the number
> of blank pages is almost constant).

4MB of zeros. I'd say that ewe have bigger problems to
solve. Detecting zero pages is actually very trivial form of
compression, and I think that we might as well do it properly, and use
something like LZW -- if we want to go that way. I think that should
be userspace problem.
							Pavel

-- 
Thanks, Sharp!
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