From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 4715A6B003D for ; Fri, 27 Mar 2009 10:53:48 -0400 (EDT) Received: from d12nrmr1607.megacenter.de.ibm.com (d12nrmr1607.megacenter.de.ibm.com [9.149.167.49]) by mtagate1.de.ibm.com (8.13.1/8.13.1) with ESMTP id n2RFACxi012856 for ; Fri, 27 Mar 2009 15:10:12 GMT Received: from d12av02.megacenter.de.ibm.com (d12av02.megacenter.de.ibm.com [9.149.165.228]) by d12nrmr1607.megacenter.de.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n2RFABTp4116714 for ; Fri, 27 Mar 2009 16:10:11 +0100 Received: from d12av02.megacenter.de.ibm.com (loopback [127.0.0.1]) by d12av02.megacenter.de.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n2RFAB2l015187 for ; Fri, 27 Mar 2009 16:10:11 +0100 Message-Id: <20090327150905.819861420@de.ibm.com> Date: Fri, 27 Mar 2009 16:09:05 +0100 From: Martin Schwidefsky Subject: [patch 0/6] Guest page hinting version 7. Sender: owner-linux-mm@kvack.org To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, virtualization@lists.osdl.org Cc: frankeh@watson.ibm.com, akpm@osdl.org, nickpiggin@yahoo.com.au, hugh@veritas.com, riel@redhat.com List-ID: Greetings, the circus is back in town -- another version of the guest page hinting patches. The patches differ from version 6 only in the kernel version, they apply against 2.6.29. My short sniff test showed that the code is still working as expected. To recap (you can skip this if you read the boiler plate of the last version of the patches): The main benefit for guest page hinting vs. the ballooner is that there is no need for a monitor that keeps track of the memory usage of all the guests, a complex algorithm that calculates the working set sizes and for the calls into the guest kernel to control the size of the balloons. The host just does normal LRU based paging. If the host picks one of the pages the guest can recreate, the host can throw it away instead of writing it to the paging device. Simple and elegant. The main disadvantage is the added complexity that is introduced to the guests memory management code to do the page state changes and to deal with discard faults. Right after booting the page states on my 256 MB z/VM guest looked like this (r=resident, p=preserved, z=zero, S=stable, U=unused, P=potentially volatile, V=volatile): |--tot--|---r---|---p---|---z---| S | 19719| 19673| 0| 46| U | 235416| 2734| 0| 232682| P | 1| 1| 0| 0| V | 7008| 7008| 0| 0| tot-> | 262144| 29416| 0| 232728| about 25% of the pages are in voltile state. After grepping through the linux source tree this picture changes: |--tot--|---r---|---p---|---z---| S | 43784| 43744| 0| 40| U | 78631| 2397| 0| 76234| P | 2| 2| 0| 0| V | 139727| 139727| 0| 0| tot-> | 262144| 185870| 0| 76274| about 75% of the pages are now volatile. Depending on the workload you will get different results. -- blue skies, Martin. "Reality continues to ruin my life." - Calvin. -- 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