Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752560Ab2KKCD3 (ORCPT ); Sat, 10 Nov 2012 21:03:29 -0500 Received: from p3plsmtps2ded02.prod.phx3.secureserver.net ([208.109.80.59]:56512 "EHLO p3plsmtps2ded02.prod.phx3.secureserver.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752339Ab2KKCD1 (ORCPT ); Sat, 10 Nov 2012 21:03:27 -0500 x-originating-ip: 72.167.245.219 From: "K. Y. Srinivasan" To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, devel@linuxdriverproject.org, olaf@aepfle.de, apw@canonical.com, andi@firstfloor.org, akpm@linux-foundation.org, linux-mm@kvack.org, kamezawa.hiroyuki@gmail.com, mhocko@suse.cz, hannes@cmpxchg.org, yinghan@google.com Cc: "K. Y. Srinivasan" Subject: [PATCH 1/1] mm: Export a function to read vm_committed_as Date: Sat, 10 Nov 2012 18:25:28 -0800 Message-Id: <1352600728-17766-1-git-send-email-kys@microsoft.com> X-Mailer: git-send-email 1.7.4.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2502 Lines: 80 It may be useful to be able to access vm_committed_as from device drivers. On the Hyper-V platform, the host has a policy engine to balance the available physical memory amongst all competing virtual machines hosted on a given node. This policy engine is driven by a number of metrics including the memory pressure reported by the guests. The balloon driver for Linux on Hyper-V uses this function to report memory pressure back to the host. Signed-off-by: K. Y. Srinivasan --- include/linux/mman.h | 2 ++ mm/mmap.c | 11 +++++++++++ mm/nommu.c | 11 +++++++++++ 3 files changed, 24 insertions(+), 0 deletions(-) diff --git a/include/linux/mman.h b/include/linux/mman.h index d09dde1..d53dc3d 100644 --- a/include/linux/mman.h +++ b/include/linux/mman.h @@ -11,6 +11,8 @@ extern int sysctl_overcommit_memory; extern int sysctl_overcommit_ratio; extern struct percpu_counter vm_committed_as; +unsigned long read_vm_committed_as(void); + static inline void vm_acct_memory(long pages) { percpu_counter_add(&vm_committed_as, pages); diff --git a/mm/mmap.c b/mm/mmap.c index 2d94235..e527239 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -89,6 +89,17 @@ int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp; /* + * A wrapper to read vm_committed_as that can be used by external modules. + */ + +unsigned long read_vm_committed_as(void) +{ + return percpu_counter_read_positive(&vm_committed_as); +} + +EXPORT_SYMBOL_GPL(read_vm_committed_as); + +/* * Check that a process has enough memory to allocate a new virtual * mapping. 0 means there is enough memory for the allocation to * succeed and -ENOMEM implies there is not. diff --git a/mm/nommu.c b/mm/nommu.c index 45131b4..dbbd0aa 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -66,6 +66,17 @@ int heap_stack_gap = 0; atomic_long_t mmap_pages_allocated; +/* + * A wrapper to read vm_committed_as that can be used by external modules. + */ + +unsigned long read_vm_committed_as(void) +{ + return percpu_counter_read_positive(&vm_committed_as); +} + +EXPORT_SYMBOL_GPL(read_vm_committed_as); + EXPORT_SYMBOL(mem_map); EXPORT_SYMBOL(num_physpages); -- 1.7.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/