From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 14 Apr 2008 10:32:31 -0700 From: Randy Dunlap Subject: Re: [PATCH 8/15] Mempolicy: Rework mempolicy Reference Counting [yet again] Message-Id: <20080414103231.60cf6005.randy.dunlap@oracle.com> In-Reply-To: <20080404150034.5442.92020.sendpatchset@localhost> References: <20080404145944.5442.2684.sendpatchset@localhost> <20080404150034.5442.92020.sendpatchset@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Lee Schermerhorn Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-numa@vger.kernel.org, eric.whitney@hp.com List-ID: On Fri, 04 Apr 2008 11:00:34 -0400 Lee Schermerhorn wrote: > PATCH 08/15 Mem Policy: rework mempolicy reference counting [yet again] > > Against: 2.6.25-rc8-mm1 > > Documentation/vm/numa_memory_policy.txt | 68 ++++++++++++++ > > Index: linux-2.6.25-rc8-mm1/Documentation/vm/numa_memory_policy.txt > =================================================================== > --- linux-2.6.25-rc8-mm1.orig/Documentation/vm/numa_memory_policy.txt 2008-04-02 17:47:15.000000000 -0400 > +++ linux-2.6.25-rc8-mm1/Documentation/vm/numa_memory_policy.txt 2008-04-02 17:47:26.000000000 -0400 > @@ -311,6 +311,74 @@ Components of Memory Policies > MPOL_PREFERRED policies that were created with an empty nodemask > (local allocation). ... > + Because of this extra reference counting, and because we must lookup > + shared policies in a tree structure under spinlock, shared policies are > + more expensive to use in the page allocation path. This is expecially especially > + true for shared policies on shared memory regions shared by tasks running > + on different NUMA nodes. This extra overhead can be avoided by always > + falling back to task or system default policy for shared memory regions, > + or by prefaulting the entire shared memory region into memory and locking > + it down. However, this might not be appropriate for all applications. > + > MEMORY POLICY APIs > > Linux supports 3 system calls for controlling memory policy. These APIS --- ~Randy -- 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