From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754549Ab2KUKWb (ORCPT ); Wed, 21 Nov 2012 05:22:31 -0500 Received: from cantor2.suse.de ([195.135.220.15]:43761 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754523Ab2KUKWZ (ORCPT ); Wed, 21 Nov 2012 05:22:25 -0500 From: Mel Gorman To: Peter Zijlstra , Andrea Arcangeli , Ingo Molnar Cc: Rik van Riel , Johannes Weiner , Hugh Dickins , Thomas Gleixner , Paul Turner , Lee Schermerhorn , Alex Shi , Linus Torvalds , Andrew Morton , Linux-MM , LKML , Mel Gorman Subject: [PATCH 17/46] mm: mempolicy: Add MPOL_MF_NOOP Date: Wed, 21 Nov 2012 10:21:23 +0000 Message-Id: <1353493312-8069-18-git-send-email-mgorman@suse.de> X-Mailer: git-send-email 1.7.9.2 In-Reply-To: <1353493312-8069-1-git-send-email-mgorman@suse.de> References: <1353493312-8069-1-git-send-email-mgorman@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lee Schermerhorn NOTE: I have not yet addressed by own review feedback of this patch. At this point I'm trying to construct a baseline tree and will apply my own review feedback later and then fold it in. This patch augments the MPOL_MF_LAZY feature by adding a "NOOP" policy to mbind(). When the NOOP policy is used with the 'MOVE and 'LAZY flags, mbind() will map the pages PROT_NONE so that they will be migrated on the next touch. This allows an application to prepare for a new phase of operation where different regions of shared storage will be assigned to worker threads, w/o changing policy. Note that we could just use "default" policy in this case. However, this also allows an application to request that pages be migrated, only if necessary, to follow any arbitrary policy that might currently apply to a range of pages, without knowing the policy, or without specifying multiple mbind()s for ranges with different policies. [ Bug in early version of mpol_parse_str() reported by Fengguang Wu. ] Bug-Reported-by: Reported-by: Fengguang Wu Signed-off-by: Lee Schermerhorn Reviewed-by: Rik van Riel Cc: Andrew Morton Cc: Linus Torvalds Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar Signed-off-by: Mel Gorman --- include/uapi/linux/mempolicy.h | 1 + mm/mempolicy.c | 11 ++++++----- 2 files changed, 7 insertions(+), 5 deletions(-) diff --git a/include/uapi/linux/mempolicy.h b/include/uapi/linux/mempolicy.h index 3e835c9..d23dca8 100644 --- a/include/uapi/linux/mempolicy.h +++ b/include/uapi/linux/mempolicy.h @@ -21,6 +21,7 @@ enum { MPOL_BIND, MPOL_INTERLEAVE, MPOL_LOCAL, + MPOL_NOOP, /* retain existing policy for range */ MPOL_MAX, /* always last member of enum */ }; diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 54bd3e5..c21e914 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -251,10 +251,10 @@ static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags, pr_debug("setting mode %d flags %d nodes[0] %lx\n", mode, flags, nodes ? nodes_addr(*nodes)[0] : -1); - if (mode == MPOL_DEFAULT) { + if (mode == MPOL_DEFAULT || mode == MPOL_NOOP) { if (nodes && !nodes_empty(*nodes)) return ERR_PTR(-EINVAL); - return NULL; /* simply delete any existing policy */ + return NULL; } VM_BUG_ON(!nodes); @@ -1147,7 +1147,7 @@ static long do_mbind(unsigned long start, unsigned long len, if (start & ~PAGE_MASK) return -EINVAL; - if (mode == MPOL_DEFAULT) + if (mode == MPOL_DEFAULT || mode == MPOL_NOOP) flags &= ~MPOL_MF_STRICT; len = (len + PAGE_SIZE - 1) & PAGE_MASK; @@ -2409,7 +2409,8 @@ static const char * const policy_modes[] = [MPOL_PREFERRED] = "prefer", [MPOL_BIND] = "bind", [MPOL_INTERLEAVE] = "interleave", - [MPOL_LOCAL] = "local" + [MPOL_LOCAL] = "local", + [MPOL_NOOP] = "noop", /* should not actually be used */ }; @@ -2460,7 +2461,7 @@ int mpol_parse_str(char *str, struct mempolicy **mpol, int no_context) break; } } - if (mode >= MPOL_MAX) + if (mode >= MPOL_MAX || mode == MPOL_NOOP) goto out; switch (mode) { -- 1.7.9.2