On Mon, Aug 12, 2013 at 08:30:02PM +0800, Wanpeng Li wrote: > On Mon, Aug 12, 2013 at 08:19:08AM -0400, Konrad Rzeszutek Wilk wrote: > >On Tue, Aug 06, 2013 at 10:24:20PM +0800, Bob Liu wrote: > >> Hi Greg, > >> > >> On 08/06/2013 09:58 PM, Greg KH wrote: > >> > On Tue, Aug 06, 2013 at 07:36:13PM +0800, Bob Liu wrote: > >> >> Dan Magenheimer extended zcache supporting both file pages and anonymous pages. > >> >> It's located in drivers/staging/zcache now. But the current version of zcache is > >> >> too complicated to be merged into upstream. > >> > > >> > Really? If this is so, I'll just go delete zcache now, I don't want to > >> > lug around dead code that will never be merged. > >> > > >> > >> Zcache in staging have a zbud allocation which is almost the same as > >> mm/zbud.c but with different API and have a frontswap backend like > >> mm/zswap.c. > >> So I'd prefer reuse mm/zbud.c and mm/zswap.c for a generic memory > >> compression solution. > >> Which means in that case, zcache in staging = mm/zswap.c + mm/zcache.c + > >> mm/zbud.c. > >> > >> But I'm not sure if there are any existing users of zcache in staging, > >> if not I can delete zcache from staging in my next version of this > >> mm/zcache.c series. > > > >I think the Samsung folks are using it (zcache). > > > > Hi Konrad, > > If there are real users using ramster? And if Xen project using zcache > and ramster in staging tree? The Xen Project has an tmem API implementation which allows the 'tmem' driver (drivers/xen/tmem.c) to use it. The Linux tmem driver implements both frontswap and cleancache APIs. That means if a guest is running under Xen it has the same benefits as if it was running baremetal and using zswap + zcache3 (what Bob posted, which is the cleancache backend) or the old zcache2 (staging/zcache). One way to think about is that the compression, deduplication, etc are all hoisted in the hypervisor while each of the guests pipes the pages up/down using hypercalls. Xen Project does not need to use zcache2 (staging/zcache) as it can get the same benefits from using tmem. Thought if the user wanted they can certainly use it and bypass tmem and either load zcache2 or zswap and zcache3 (the one Bob posted). In regards to "real users using RAMster" - I am surmising you are wondering whether Oracle is offering this as a supported product to customers? The answer to that is no at this time as it is still in development and we would want it to be out of that before Oracle supports it in its distributions. Now "would want" and the reality of what can be done right now is a bit disjoint. I think that the next step is concentrating on making zswap awesome and also make the zcache3 (the patches that Bob posted) in shape to be merged in mm. It would be fantastic if folks took a look at the patches and gave comments. Thanks! P.S. Greg, since the Samsung folks are not using it, and we (Oracle) can patch our distro kernel to provide smörgåsbord of zcache2, zswap and zcache3, even zcache1 if needed. I think it is safe to delete staging/zcache and focus on getting the zcache3 (Bob's patchset) upstream. -- 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