From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 24 Mar 2008 14:52:09 -0700 From: Andrew Morton Subject: Re: [RFC/PATCH 02/15 v2] preparation: host memory management changes for s390 kvm Message-Id: <20080324145209.23920166.akpm@linux-foundation.org> In-Reply-To: <1206205359.7177.84.camel@cotte.boeblingen.de.ibm.com> References: <1206030270.6690.51.camel@cotte.boeblingen.de.ibm.com> <1206203560.7177.45.camel@cotte.boeblingen.de.ibm.com> <1206205359.7177.84.camel@cotte.boeblingen.de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Carsten Otte Cc: virtualization@lists.linux-foundation.org, kvm-devel@lists.sourceforge.net, avi@qumranet.com, npiggin@suse.de, hugh@veritas.com, linux-mm@kvack.org, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, os@de.ibm.com, borntraeger@de.ibm.com, hollisb@us.ibm.com, EHRHARDT@de.ibm.com, jeroney@us.ibm.com, aliguori@us.ibm.com, jblunck@suse.de, rvdheij@gmail.com, rusty@rustcorp.com.au, arnd@arndb.de, xiantao.zhang@intel.com List-ID: On Sat, 22 Mar 2008 18:02:39 +0100 Carsten Otte wrote: > From: Heiko Carstens > From: Christian Borntraeger > > This patch changes the s390 memory management defintions to use the pgste field > for dirty and reference bit tracking of host and guest code. Usually on s390, > dirty and referenced are tracked in storage keys, which belong to the physical > page. This changes with virtualization: The guest and host dirty/reference bits > are defined to be the logical OR of the values for the mapping and the physical > page. This patch implements the necessary changes in pgtable.h for s390. > > > There is a common code change in mm/rmap.c, the call to page_test_and_clear_young > must be moved. This is a no-op for all architecture but s390. page_referenced > checks the referenced bits for the physiscal page and for all mappings: > o The physical page is checked with page_test_and_clear_young. > o The mappings are checked with ptep_test_and_clear_young and friends. > > Without pgstes (the current implementation on Linux s390) the physical page > check is implemented but the mapping callbacks are no-ops because dirty > and referenced are not tracked in the s390 page tables. The pgstes introduces > guest and host dirty and reference bits for s390 in the host mapping. These > mapping must be checked before page_test_and_clear_young resets the reference > bit. > > ... > > --- linux-host.orig/mm/rmap.c > +++ linux-host/mm/rmap.c > @@ -413,9 +413,6 @@ int page_referenced(struct page *page, i > { > int referenced = 0; > > - if (page_test_and_clear_young(page)) > - referenced++; > - > if (TestClearPageReferenced(page)) > referenced++; > > @@ -433,6 +430,10 @@ int page_referenced(struct page *page, i > unlock_page(page); > } > } > + > + if (page_test_and_clear_young(page)) > + referenced++; > + > return referenced; > } ack. -- 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