Zcache is the first Linux memory management capability that uses compression to dramatically increase RAM efficiency forboth the page cache and for swap pages. The mechanism has been in staging since 2.6.39, but has been complemented only by a very primitive policy. The key to promoting zcache to a full kernel citizen and for turning zcache into an enterprise-ready default feature is a bulletproof ""first do no harm"" policy that must improve performance on many workloads while avoiding performance degradation on others. We will present how zcache works, discuss core kernel memory management policies and how they might be extended to ""harden"" zcache, and solicit discussion on improving zcache, as well as its Transcendent Memory brethren: RAMster, which uses zcache and kernel sockets to load-balance RAM across a cluster, and Xen and KVM tmem, which provide similar function across VMs.
