> From: Robert Jennings [mailto:r...@linux.vnet.ibm.com] > Sent: Thursday, March 14, 2013 7:21 AM > To: Bob > Cc: Seth Jennings; Dan Magenheimer; minc...@kernel.org; Nitin Gupta; Konrad > Wilk; linux...@kvack.org; > linux-kernel@vger.kernel.org; Bob Liu; Luigi Semenzato; Mel Gorman > Subject: Re: zsmalloc limitations and related topics > > * Bob (bob....@oracle.com) wrote: > > On 03/14/2013 06:59 AM, Seth Jennings wrote: > > >On 03/13/2013 03:02 PM, Dan Magenheimer wrote: > > >>>From: Robert Jennings [mailto:r...@linux.vnet.ibm.com] > > >>>Subject: Re: zsmalloc limitations and related topics > > >> > <snip> > > >>Yes. And add pageframe-reclaim to this list of things that > > >>zsmalloc should do but currently cannot do. > > > > > >The real question is why is pageframe-reclaim a requirement? What > > >operation needs this feature? > > > > > >AFAICT, the pageframe-reclaim requirements is derived from the > > >assumption that some external control path should be able to tell > > >zswap/zcache to evacuate a page, like the shrinker interface. But this > > >introduces a new and complex problem in designing a policy that doesn't > > >shrink the zpage pool so aggressively that it is useless. > > > > > >Unless there is another reason for this functionality I'm missing. > > > > > > > Perhaps it's needed if the user want to enable/disable the memory > > compression feature dynamically. > > Eg, use it as a module instead of recompile the kernel or even > > reboot the system.
It's worth thinking about: Under what circumstances would a user want to turn off compression? While unloading a compression module should certainly be allowed if it makes a user comfortable, in my opinion, if a user wants to do that, we have done our job poorly (or there is a bug). > To unload zswap all that is needed is to perform writeback on the pages > held in the cache, this can be done by extending the existing writeback > code. Actually, frontswap supports this directly. See frontswap_shrink. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
