Hi Luigi, On Wed, Aug 14, 2013 at 08:53:31AM -0700, Luigi Semenzato wrote: > During earlier discussions of zswap there was a plan to make it work > with zsmalloc as an option instead of zbud. Does zbud work for AFAIR, it was not an optoin but zsmalloc was must but there were several objections because zswap's notable feature is to dump compressed object to real swap storage. For that, zswap needs to store bounded objects in a zpage so that dumping could be bounded, too. Otherwise, it could encounter OOM easily. > compression factors better than 2:1? I have the impression (maybe > wrong) that it does not. In our use of zram (Chrome OS) typical Since zswap changed allocator from zsmalloc to zbud, I didn't follow because I had no interest of low compressoin ratio allocator so I have no idea of status of zswap at a moment but I guess it would be still 2:1. > overall compression ratios are between 2.5:1 and 3:1. We would hate > to waste that memory if we switch to zswap. If you have real swap storage, zswap might be better although I have no number but real swap is money for embedded system and it has sudden garbage collection on firmware side if we use eMMC or SSD so that it could affect system latency. Morever, if we start to use real swap, maybe we should encrypt the data and it would be severe overhead(CPU and Power). And what I am considering after promoting for zram feature is asynchronous I/O and it's possible because zram is block device. Thanks! -- Kind regards, Minchan Kim -- 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>