Hi, On Fri, Aug 16, 2013 at 10:02:08AM +0800, Wanpeng Li wrote: > Hi Minchan, > On Thu, Aug 15, 2013 at 01:17:53AM +0900, Minchan Kim wrote: > >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). > > > > Why real swap for embedded system need encrypt the data? I think there > is no encrypt for data against server and desktop. I have used some portable device but suddenly, I lost it or was stolen. A hacker can pick it up and read my swap and found my precious information. I don't want it. I guess it's one of reason ChromeOS don't want to use real swap. https://groups.google.com/a/chromium.org/forum/#!msg/chromium-os-discuss/92Fvi4Ezego/ZvbrC3L2FG4J > > >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> > -- 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>