From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <444DCD87.2030307@yahoo.com.au> Date: Tue, 25 Apr 2006 17:19:35 +1000 From: Nick Piggin MIME-Version: 1.0 Subject: Re: Page host virtual assist patches. References: <20060424123412.GA15817@skybase> <20060424180138.52e54e5c.akpm@osdl.org> In-Reply-To: <20060424180138.52e54e5c.akpm@osdl.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Martin Schwidefsky , linux-mm@kvack.org, frankeh@watson.ibm.com, rhim@cc.gatech.edu List-ID: Andrew Morton wrote: > Martin Schwidefsky wrote: > >> The basic idea of host virtual assist (hva) is to give a host system >> which virtualizes the memory of its guest systems on a per page basis >> usage information for the guest pages. The host can then use this >> information to optimize the management of guest pages, in particular >> the paging. This optimizations can be used for unused (free) guest >> pages, for clean page cache pages, and for clean swap cache pages. > > > This is pretty significant stuff. It sounds like something which needs to > be worked through with other possible users - UML, Xen, vware, etc. > > How come the reclaim has to be done in the host? I'd have thought that a > much simpler approach would be to perform a host->guest upcall saying > either "try to free up this many pages" or "free this page" or "free this > vector of pages"? Definitely. The current patches seem like just an extra layer to do everything we can already -- reclaim unused pages and populate them again when they get touched. And complex they are. Having the core VM have to know about all this weird stuff seems... not good. -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org