Hi Andrew and Linux -- I thought I'd try to summarize for you the current status resulting from the 100+ emails stemming from the original git-pull request. EXECUTIVE SUMMARY (djm bias noted) Frontswap is part 2 of 2 of transcendent memory; cleancache (merged at 3.0) is part 1. Frontswap consists primarily of a handful of hooks in the swap subsystem, which end in a frontswap_ops function vector. If no "backend" registers the vector, all hooks become no-ops. Current in-tree users are Xen, and "zcache" (in staging), but two other users, RAMster and KVM, are under development in public git trees. Xen is by far the most mature user for frontswap. If you count Xen as a valid user, you should IMHO seriously consider the commit-set, as-is, as ready to merge (even for 3.2), especially since shipping distros already include it. If one disregards Xen, there's a lot more work to be done to prove frontswap should be merged. RESPONDED TO SUPPORT FRONTSWAP Jan Beulich (Novell): frontswap in OpenSuse for two years Brian King (IBM): wants frontswap/zcache for Linux on Power Sasha Levin (*): actively developing KVM+tmem, wants frontswap Neo Jia (*): actively developing KVM+tmem, wants frontswap Nitin Gupta (UMass): zcache co-designer, better than zram Seth Jennings (IBM): actively improving zcache Ed Tomlinson (* user): wants frontswap instead of zram Kurt Hackel (Oracle): shipping Oracle VM product supports frontswap Avi Miller (Oracle): Beta of next Oracle kernel supports frontswap Note: Oracle, as a company, has committed to support frontswap. * affiliation unspecified (but not Oracle ;-) LAST KNOWN POSITION OF AD HOC ARCHITECTURE REVIEW GROUP Andrea: zcache still needs a lot of work, has ideas for future related swap improvements, "now that you cleared the fact there is no API/ABI in [zcache] to worry about, frankly, I'm a lot more happy now", "don't want to stifle innovation by saying no to something that makes sense and is free to evolve", "this overall sounds very positive (or at least better than neutral) to me"... I also think Andrea's last remaining issue (need batching for KVM) now has a viable solution that works with no frontswap commit-set changes, but Andrea has not confirmed Rik: list of concerns, but I think all were discussed and resolved later in the thread (except possibly wanting to see more non-Xen benchmarks), no final response from Rik James: wants more benchmarks especially for zcache, thinks ABI should be proven to be useful to KVM before frontswap gets merged Hannes: Nacked, but I think raised issues were later discussed and resolved in the thread, with no further response from Hannes (If anyone quoted here feels misquoted/missummarized, please feel free to respond.) -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href