From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1032214Ab2CSR2p (ORCPT ); Mon, 19 Mar 2012 13:28:45 -0400 Received: from merlin.infradead.org ([205.233.59.134]:53755 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031961Ab2CSR2n convert rfc822-to-8bit (ORCPT ); Mon, 19 Mar 2012 13:28:43 -0400 Message-ID: <1332178095.18960.354.camel@twins> Subject: Re: [RFC][PATCH 10/26] mm, mpol: Make mempolicy home-node aware From: Peter Zijlstra To: Christoph Lameter Cc: Linus Torvalds , Andrew Morton , Thomas Gleixner , Ingo Molnar , Paul Turner , Suresh Siddha , Mike Galbraith , "Paul E. McKenney" , Lai Jiangshan , Dan Smith , Bharata B Rao , Lee Schermerhorn , Andrea Arcangeli , Rik van Riel , Johannes Weiner , linux-kernel@vger.kernel.org, linux-mm@kvack.org Date: Mon, 19 Mar 2012 18:28:15 +0100 In-Reply-To: <1332176969.18960.351.camel@twins> References: <20120316144028.036474157@chello.nl> <20120316144240.763518310@chello.nl> <1331932375.18960.237.camel@twins> <1332165959.18960.340.camel@twins> <1332170628.18960.349.camel@twins> <1332176969.18960.351.camel@twins> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2012-03-19 at 18:09 +0100, Peter Zijlstra wrote: > On Mon, 2012-03-19 at 10:31 -0500, Christoph Lameter wrote: > > > MPOL_DEFAULT is a certain type of behavior right now that applications > > rely on. If you change that then these applications will no longer work as > > expected. > > > > MPOL_DEFAULT is currently set to be the default policy on bootup. You can > > change that of course and allow setting MPOL_DEFAULT manually for > > applications that rely on old behavor. Instead set the default behavior on > > bootup for MPOL_HOME_NODE. > > > > So the default system behavior would be MPOL_HOME_NODE but it could be > > overriding by numactl to allow old apps to run as they are used to run. > > Ah, OK. Although that's a mightily confusing usage of the word DEFAULT. > How about instead we make MPOL_LOCAL a real policy and allow explicitly > setting that? I suspect something like the below might suffice.. still need to test it though. --- --- a/include/linux/mempolicy.h +++ b/include/linux/mempolicy.h @@ -21,6 +21,7 @@ enum { MPOL_BIND, MPOL_INTERLEAVE, MPOL_NOOP, /* retain existing policy for range */ + MPOL_LOCAL, MPOL_MAX, /* always last member of enum */ }; --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -285,6 +285,10 @@ struct mempolicy *mpol_new(unsigned shor (flags & MPOL_F_RELATIVE_NODES))) return ERR_PTR(-EINVAL); } + } else if (mode == MPOL_LOCAL) { + if (!nodes_empty(*nodes)) + return ERR_PTR(-EINVAL); + mode = MPOL_PREFERRED; } else if (nodes_empty(*nodes)) return ERR_PTR(-EINVAL); policy = kmem_cache_alloc(policy_cache, GFP_KERNEL | __GFP_ZERO); @@ -2446,7 +2450,6 @@ void numa_default_policy(void) * "local" is pseudo-policy: MPOL_PREFERRED with MPOL_F_LOCAL flag * Used only for mpol_parse_str() and mpol_to_str() */ -#define MPOL_LOCAL MPOL_MAX static const char * const policy_modes[] = { [MPOL_DEFAULT] = "default", @@ -2499,12 +2502,12 @@ int mpol_parse_str(char *str, struct mem if (flags) *flags++ = '\0'; /* terminate mode string */ - for (mode = 0; mode <= MPOL_LOCAL; mode++) { + for (mode = 0; mode < MPOL_MAX; mode++) { if (!strcmp(str, policy_modes[mode])) { break; } } - if (mode > MPOL_LOCAL) + if (mode >= MPOL_MAX) goto out; switch (mode) {