On Wed 2012-04-11 13:28:39, Adrian Hunter wrote: > On 04/04/12 15:47, Arnd Bergmann wrote: > > On Wednesday 04 April 2012, Adrian Hunter wrote: > >> On 30/03/12 21:50, Arnd Bergmann wrote: > >>> (sorry for the duplicated email, this corrects the address of the android > >>> kernel team, please reply here) > >>> > >>> On Friday 30 March 2012, Arnd Bergmann wrote: > >>> > >>> We've had a discussion in the Linaro storage team (Saugata, Venkat and me, > >>> with Luca joining in on the discussion) about swapping to flash based media > >>> such as eMMC. This is a summary of what we found and what we think should > >>> be done. If people agree that this is a good idea, we can start working > >>> on it. > >> > >> There is mtdswap. > > > > Ah, very interesting. I wasn't aware of that. Obviously we can't directly > > use it on block devices that have their own garbage collection and wear > > leveling built into them, but it's interesting to see how this was solved > > before. > > > > While we could build something similar that remaps blocks between an > > eMMC device and the logical swap space that is used by the mm code, > > my feeling is that it would be easier to modify the swap code itself > > to do the right thing. > > > >> Also the old Nokia N900 had swap to eMMC. > >> > >> The last I heard was that swap was considered to be simply too slow on hand > >> held devices. > > > > That's the part that we want to solve here. It has nothing to do with > > handheld devices, but more with specific incompatibilities of the > > block allocation in the swap code vs. what an eMMC device expects > > to see for fast operation. If you write data in the wrong order on > > flash devices, you get long delays that you don't get when you do > > it the right way. The same problem exists for file systems, and is > > being addressed there as well. > > > >> As systems adopt more RAM, isn't there a decreasing demand for swap? > > > > No. You would never be able to make hibernate work, no matter how much > > RAM you add ;-) > > Have you considered making hibernate work without swap? It does work without swap. See userland suspend packages, where you write the image is up-to you. 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@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>