From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932156Ab3HGQ3X (ORCPT ); Wed, 7 Aug 2013 12:29:23 -0400 Received: from mga14.intel.com ([143.182.124.37]:36675 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756793Ab3HGQ3V (ORCPT ); Wed, 7 Aug 2013 12:29:21 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.89,834,1367996400"; d="scan'208";a="278979095" From: "Kirill A. Shutemov" To: Jan Kara Cc: "Kirill A. Shutemov" , Andrea Arcangeli , Andrew Morton , Al Viro , Hugh Dickins , Wu Fengguang , Jan Kara , Mel Gorman , linux-mm@kvack.org, Andi Kleen , Matthew Wilcox , "Kirill A. Shutemov" , Hillf Danton , Dave Hansen , Ning Qu , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20130805111739.GA25691@quack.suse.cz> References: <1375582645-29274-1-git-send-email-kirill.shutemov@linux.intel.com> <1375582645-29274-2-git-send-email-kirill.shutemov@linux.intel.com> <20130805111739.GA25691@quack.suse.cz> Subject: Re: [PATCH 01/23] radix-tree: implement preload for multiple contiguous elements Content-Transfer-Encoding: 7bit Message-Id: <20130807163236.0F17DE0090@blue.fi.intel.com> Date: Wed, 7 Aug 2013 19:32:36 +0300 (EEST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jan Kara wrote: > On Sun 04-08-13 05:17:03, Kirill A. Shutemov wrote: > > From: "Kirill A. Shutemov" > > > > The radix tree is variable-height, so an insert operation not only has > > to build the branch to its corresponding item, it also has to build the > > branch to existing items if the size has to be increased (by > > radix_tree_extend). > > > > The worst case is a zero height tree with just a single item at index 0, > > and then inserting an item at index ULONG_MAX. This requires 2 new branches > > of RADIX_TREE_MAX_PATH size to be created, with only the root node shared. > > > > Radix tree is usually protected by spin lock. It means we want to > > pre-allocate required memory before taking the lock. > > > > Currently radix_tree_preload() only guarantees enough nodes to insert > > one element. It's a hard limit. For transparent huge page cache we want > > to insert HPAGE_PMD_NR (512 on x86-64) entries to address_space at once. > > > > This patch introduces radix_tree_preload_count(). It allows to > > preallocate nodes enough to insert a number of *contiguous* elements. > > The feature costs about 5KiB per-CPU, details below. > > > > Worst case for adding N contiguous items is adding entries at indexes > > (ULONG_MAX - N) to ULONG_MAX. It requires nodes to insert single worst-case > > item plus extra nodes if you cross the boundary from one node to the next. > > > > Preload uses per-CPU array to store nodes. The total cost of preload is > > "array size" * sizeof(void*) * NR_CPUS. We want to increase array size > > to be able to handle 512 entries at once. > > > > Size of array depends on system bitness and on RADIX_TREE_MAP_SHIFT. > > > > We have three possible RADIX_TREE_MAP_SHIFT: > > > > #ifdef __KERNEL__ > > #define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6) > > #else > > #define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */ > > #endif > > > > On 64-bit system: > > For RADIX_TREE_MAP_SHIFT=3, old array size is 43, new is 107. > > For RADIX_TREE_MAP_SHIFT=4, old array size is 31, new is 63. > > For RADIX_TREE_MAP_SHIFT=6, old array size is 21, new is 30. > > > > On 32-bit system: > > For RADIX_TREE_MAP_SHIFT=3, old array size is 21, new is 84. > > For RADIX_TREE_MAP_SHIFT=4, old array size is 15, new is 46. > > For RADIX_TREE_MAP_SHIFT=6, old array size is 11, new is 19. > > > > On most machines we will have RADIX_TREE_MAP_SHIFT=6. In this case, > > on 64-bit system the per-CPU feature overhead is > > for preload array: > > (30 - 21) * sizeof(void*) = 72 bytes > > plus, if the preload array is full > > (30 - 21) * sizeof(struct radix_tree_node) = 9 * 560 = 5040 bytes > > total: 5112 bytes > > > > on 32-bit system the per-CPU feature overhead is > > for preload array: > > (19 - 11) * sizeof(void*) = 32 bytes > > plus, if the preload array is full > > (19 - 11) * sizeof(struct radix_tree_node) = 8 * 296 = 2368 bytes > > total: 2400 bytes > > > > Since only THP uses batched preload at the moment, we disable (set max > > preload to 1) it if !CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE. This can be > > changed in the future. > > > > Signed-off-by: Matthew Wilcox > > Signed-off-by: Kirill A. Shutemov > > Acked-by: Dave Hansen > > --- > > include/linux/radix-tree.h | 11 +++++++++++ > > lib/radix-tree.c | 41 ++++++++++++++++++++++++++++++++--------- > > 2 files changed, 43 insertions(+), 9 deletions(-) > ... > > diff --git a/lib/radix-tree.c b/lib/radix-tree.c > > index 7811ed3..99ab73c 100644 > > --- a/lib/radix-tree.c > > +++ b/lib/radix-tree.c > > @@ -82,16 +82,24 @@ static struct kmem_cache *radix_tree_node_cachep; > > * The worst case is a zero height tree with just a single item at index 0, > > * and then inserting an item at index ULONG_MAX. This requires 2 new branches > > * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared. > > + * > > + * Worst case for adding N contiguous items is adding entries at indexes > > + * (ULONG_MAX - N) to ULONG_MAX. It requires nodes to insert single worst-case > > + * item plus extra nodes if you cross the boundary from one node to the next. > > + * > > * Hence: > > */ > > -#define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1) > > +#define RADIX_TREE_PRELOAD_MIN (RADIX_TREE_MAX_PATH * 2 - 1) > > +#define RADIX_TREE_PRELOAD_MAX \ > > + (RADIX_TREE_PRELOAD_MIN + \ > > + DIV_ROUND_UP(RADIX_TREE_PRELOAD_NR - 1, RADIX_TREE_MAP_SIZE)) > Umm, is this really correct? I see two problems: > 1) You may need internal tree nodes at various levels but you seem to > account only for the level 1. > 2) The rounding doesn't seem right because RADIX_TREE_MAP_SIZE+2 nodes may > require 3 nodes at level 1 if the indexes are like: > i_0 | i_1 .. i_{RADIX_TREE_MAP_SIZE} | i_{RADIX_TREE_MAP_SIZE+1} > ^ ^ > node boundary node boundary My bad. Let's try to calculate once again. We want to insert N contiguous items without restriction on alignment. Let's limit N <= 1UL << (2 * RADIX_TREE_MAP_SHIFT), without CONFIG_BASE_SMALL it's 4096. It will simplify calculation a bit. Worst case scenario, I can imagine, is tree with only one element at index 0 and we add N items where at least one index requires max tree high and we cross boundary between items in root node. Basically, at least one index is less then 1UL << ((RADIX_TREE_MAX_PATH - 1) * RADIX_TREE_MAP_SHIFT) and one equal or more. In this case we need: - RADIX_TREE_MAX_PATH nodes to build new path to item with index 0; - DIV_ROUND_UP(N, RADIX_TREE_MAP_SIZE) nodes for last level nodes for new items; - 2 * (RADIX_TREE_MAX_PATH - 2) nodes to build path to last level nodes. (-2, because root node and last level nodes are already accounted). The macro: #define RADIX_TREE_PRELOAD_MAX \ ( RADIX_TREE_MAX_PATH + \ DIV_ROUND_UP(RADIX_TREE_PRELOAD_NR, RADIX_TREE_MAP_SIZE) + \ 2 * (RADIX_TREE_MAX_PATH - 2) ) For 64-bit system and N=512, RADIX_TREE_PRELOAD_MAX is 37. Does it sound correct? Any thoughts? -- Kirill A. Shutemov From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Kirill A. Shutemov" Subject: Re: [PATCH 01/23] radix-tree: implement preload for multiple contiguous elements Date: Wed, 7 Aug 2013 19:32:36 +0300 (EEST) Message-ID: <20130807163236.0F17DE0090@blue.fi.intel.com> References: <1375582645-29274-1-git-send-email-kirill.shutemov@linux.intel.com> <1375582645-29274-2-git-send-email-kirill.shutemov@linux.intel.com> <20130805111739.GA25691@quack.suse.cz> Content-Transfer-Encoding: 7bit Cc: "Kirill A. Shutemov" , Andrea Arcangeli , Andrew Morton , Al Viro , Hugh Dickins , Wu Fengguang , Jan Kara , Mel Gorman , linux-mm@kvack.org, Andi Kleen , Matthew Wilcox , "Kirill A. Shutemov" , Hillf Danton , Dave Hansen , Ning Qu , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Jan Kara Return-path: In-Reply-To: <20130805111739.GA25691@quack.suse.cz> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org Jan Kara wrote: > On Sun 04-08-13 05:17:03, Kirill A. Shutemov wrote: > > From: "Kirill A. Shutemov" > > > > The radix tree is variable-height, so an insert operation not only has > > to build the branch to its corresponding item, it also has to build the > > branch to existing items if the size has to be increased (by > > radix_tree_extend). > > > > The worst case is a zero height tree with just a single item at index 0, > > and then inserting an item at index ULONG_MAX. This requires 2 new branches > > of RADIX_TREE_MAX_PATH size to be created, with only the root node shared. > > > > Radix tree is usually protected by spin lock. It means we want to > > pre-allocate required memory before taking the lock. > > > > Currently radix_tree_preload() only guarantees enough nodes to insert > > one element. It's a hard limit. For transparent huge page cache we want > > to insert HPAGE_PMD_NR (512 on x86-64) entries to address_space at once. > > > > This patch introduces radix_tree_preload_count(). It allows to > > preallocate nodes enough to insert a number of *contiguous* elements. > > The feature costs about 5KiB per-CPU, details below. > > > > Worst case for adding N contiguous items is adding entries at indexes > > (ULONG_MAX - N) to ULONG_MAX. It requires nodes to insert single worst-case > > item plus extra nodes if you cross the boundary from one node to the next. > > > > Preload uses per-CPU array to store nodes. The total cost of preload is > > "array size" * sizeof(void*) * NR_CPUS. We want to increase array size > > to be able to handle 512 entries at once. > > > > Size of array depends on system bitness and on RADIX_TREE_MAP_SHIFT. > > > > We have three possible RADIX_TREE_MAP_SHIFT: > > > > #ifdef __KERNEL__ > > #define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6) > > #else > > #define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */ > > #endif > > > > On 64-bit system: > > For RADIX_TREE_MAP_SHIFT=3, old array size is 43, new is 107. > > For RADIX_TREE_MAP_SHIFT=4, old array size is 31, new is 63. > > For RADIX_TREE_MAP_SHIFT=6, old array size is 21, new is 30. > > > > On 32-bit system: > > For RADIX_TREE_MAP_SHIFT=3, old array size is 21, new is 84. > > For RADIX_TREE_MAP_SHIFT=4, old array size is 15, new is 46. > > For RADIX_TREE_MAP_SHIFT=6, old array size is 11, new is 19. > > > > On most machines we will have RADIX_TREE_MAP_SHIFT=6. In this case, > > on 64-bit system the per-CPU feature overhead is > > for preload array: > > (30 - 21) * sizeof(void*) = 72 bytes > > plus, if the preload array is full > > (30 - 21) * sizeof(struct radix_tree_node) = 9 * 560 = 5040 bytes > > total: 5112 bytes > > > > on 32-bit system the per-CPU feature overhead is > > for preload array: > > (19 - 11) * sizeof(void*) = 32 bytes > > plus, if the preload array is full > > (19 - 11) * sizeof(struct radix_tree_node) = 8 * 296 = 2368 bytes > > total: 2400 bytes > > > > Since only THP uses batched preload at the moment, we disable (set max > > preload to 1) it if !CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE. This can be > > changed in the future. > > > > Signed-off-by: Matthew Wilcox > > Signed-off-by: Kirill A. Shutemov > > Acked-by: Dave Hansen > > --- > > include/linux/radix-tree.h | 11 +++++++++++ > > lib/radix-tree.c | 41 ++++++++++++++++++++++++++++++++--------- > > 2 files changed, 43 insertions(+), 9 deletions(-) > ... > > diff --git a/lib/radix-tree.c b/lib/radix-tree.c > > index 7811ed3..99ab73c 100644 > > --- a/lib/radix-tree.c > > +++ b/lib/radix-tree.c > > @@ -82,16 +82,24 @@ static struct kmem_cache *radix_tree_node_cachep; > > * The worst case is a zero height tree with just a single item at index 0, > > * and then inserting an item at index ULONG_MAX. This requires 2 new branches > > * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared. > > + * > > + * Worst case for adding N contiguous items is adding entries at indexes > > + * (ULONG_MAX - N) to ULONG_MAX. It requires nodes to insert single worst-case > > + * item plus extra nodes if you cross the boundary from one node to the next. > > + * > > * Hence: > > */ > > -#define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1) > > +#define RADIX_TREE_PRELOAD_MIN (RADIX_TREE_MAX_PATH * 2 - 1) > > +#define RADIX_TREE_PRELOAD_MAX \ > > + (RADIX_TREE_PRELOAD_MIN + \ > > + DIV_ROUND_UP(RADIX_TREE_PRELOAD_NR - 1, RADIX_TREE_MAP_SIZE)) > Umm, is this really correct? I see two problems: > 1) You may need internal tree nodes at various levels but you seem to > account only for the level 1. > 2) The rounding doesn't seem right because RADIX_TREE_MAP_SIZE+2 nodes may > require 3 nodes at level 1 if the indexes are like: > i_0 | i_1 .. i_{RADIX_TREE_MAP_SIZE} | i_{RADIX_TREE_MAP_SIZE+1} > ^ ^ > node boundary node boundary My bad. Let's try to calculate once again. We want to insert N contiguous items without restriction on alignment. Let's limit N <= 1UL << (2 * RADIX_TREE_MAP_SHIFT), without CONFIG_BASE_SMALL it's 4096. It will simplify calculation a bit. Worst case scenario, I can imagine, is tree with only one element at index 0 and we add N items where at least one index requires max tree high and we cross boundary between items in root node. Basically, at least one index is less then 1UL << ((RADIX_TREE_MAX_PATH - 1) * RADIX_TREE_MAP_SHIFT) and one equal or more. In this case we need: - RADIX_TREE_MAX_PATH nodes to build new path to item with index 0; - DIV_ROUND_UP(N, RADIX_TREE_MAP_SIZE) nodes for last level nodes for new items; - 2 * (RADIX_TREE_MAX_PATH - 2) nodes to build path to last level nodes. (-2, because root node and last level nodes are already accounted). The macro: #define RADIX_TREE_PRELOAD_MAX \ ( RADIX_TREE_MAX_PATH + \ DIV_ROUND_UP(RADIX_TREE_PRELOAD_NR, RADIX_TREE_MAP_SIZE) + \ 2 * (RADIX_TREE_MAX_PATH - 2) ) For 64-bit system and N=512, RADIX_TREE_PRELOAD_MAX is 37. Does it sound correct? Any thoughts? -- Kirill A. Shutemov -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx173.postini.com [74.125.245.173]) by kanga.kvack.org (Postfix) with SMTP id 14E4D6B00B1 for ; Wed, 7 Aug 2013 12:29:21 -0400 (EDT) From: "Kirill A. Shutemov" In-Reply-To: <20130805111739.GA25691@quack.suse.cz> References: <1375582645-29274-1-git-send-email-kirill.shutemov@linux.intel.com> <1375582645-29274-2-git-send-email-kirill.shutemov@linux.intel.com> <20130805111739.GA25691@quack.suse.cz> Subject: Re: [PATCH 01/23] radix-tree: implement preload for multiple contiguous elements Content-Transfer-Encoding: 7bit Message-Id: <20130807163236.0F17DE0090@blue.fi.intel.com> Date: Wed, 7 Aug 2013 19:32:36 +0300 (EEST) Sender: owner-linux-mm@kvack.org List-ID: To: Jan Kara Cc: "Kirill A. Shutemov" , Andrea Arcangeli , Andrew Morton , Al Viro , Hugh Dickins , Wu Fengguang , Mel Gorman , linux-mm@kvack.org, Andi Kleen , Matthew Wilcox , "Kirill A. Shutemov" , Hillf Danton , Dave Hansen , Ning Qu , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Jan Kara wrote: > On Sun 04-08-13 05:17:03, Kirill A. Shutemov wrote: > > From: "Kirill A. Shutemov" > > > > The radix tree is variable-height, so an insert operation not only has > > to build the branch to its corresponding item, it also has to build the > > branch to existing items if the size has to be increased (by > > radix_tree_extend). > > > > The worst case is a zero height tree with just a single item at index 0, > > and then inserting an item at index ULONG_MAX. This requires 2 new branches > > of RADIX_TREE_MAX_PATH size to be created, with only the root node shared. > > > > Radix tree is usually protected by spin lock. It means we want to > > pre-allocate required memory before taking the lock. > > > > Currently radix_tree_preload() only guarantees enough nodes to insert > > one element. It's a hard limit. For transparent huge page cache we want > > to insert HPAGE_PMD_NR (512 on x86-64) entries to address_space at once. > > > > This patch introduces radix_tree_preload_count(). It allows to > > preallocate nodes enough to insert a number of *contiguous* elements. > > The feature costs about 5KiB per-CPU, details below. > > > > Worst case for adding N contiguous items is adding entries at indexes > > (ULONG_MAX - N) to ULONG_MAX. It requires nodes to insert single worst-case > > item plus extra nodes if you cross the boundary from one node to the next. > > > > Preload uses per-CPU array to store nodes. The total cost of preload is > > "array size" * sizeof(void*) * NR_CPUS. We want to increase array size > > to be able to handle 512 entries at once. > > > > Size of array depends on system bitness and on RADIX_TREE_MAP_SHIFT. > > > > We have three possible RADIX_TREE_MAP_SHIFT: > > > > #ifdef __KERNEL__ > > #define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6) > > #else > > #define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */ > > #endif > > > > On 64-bit system: > > For RADIX_TREE_MAP_SHIFT=3, old array size is 43, new is 107. > > For RADIX_TREE_MAP_SHIFT=4, old array size is 31, new is 63. > > For RADIX_TREE_MAP_SHIFT=6, old array size is 21, new is 30. > > > > On 32-bit system: > > For RADIX_TREE_MAP_SHIFT=3, old array size is 21, new is 84. > > For RADIX_TREE_MAP_SHIFT=4, old array size is 15, new is 46. > > For RADIX_TREE_MAP_SHIFT=6, old array size is 11, new is 19. > > > > On most machines we will have RADIX_TREE_MAP_SHIFT=6. In this case, > > on 64-bit system the per-CPU feature overhead is > > for preload array: > > (30 - 21) * sizeof(void*) = 72 bytes > > plus, if the preload array is full > > (30 - 21) * sizeof(struct radix_tree_node) = 9 * 560 = 5040 bytes > > total: 5112 bytes > > > > on 32-bit system the per-CPU feature overhead is > > for preload array: > > (19 - 11) * sizeof(void*) = 32 bytes > > plus, if the preload array is full > > (19 - 11) * sizeof(struct radix_tree_node) = 8 * 296 = 2368 bytes > > total: 2400 bytes > > > > Since only THP uses batched preload at the moment, we disable (set max > > preload to 1) it if !CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE. This can be > > changed in the future. > > > > Signed-off-by: Matthew Wilcox > > Signed-off-by: Kirill A. Shutemov > > Acked-by: Dave Hansen > > --- > > include/linux/radix-tree.h | 11 +++++++++++ > > lib/radix-tree.c | 41 ++++++++++++++++++++++++++++++++--------- > > 2 files changed, 43 insertions(+), 9 deletions(-) > ... > > diff --git a/lib/radix-tree.c b/lib/radix-tree.c > > index 7811ed3..99ab73c 100644 > > --- a/lib/radix-tree.c > > +++ b/lib/radix-tree.c > > @@ -82,16 +82,24 @@ static struct kmem_cache *radix_tree_node_cachep; > > * The worst case is a zero height tree with just a single item at index 0, > > * and then inserting an item at index ULONG_MAX. This requires 2 new branches > > * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared. > > + * > > + * Worst case for adding N contiguous items is adding entries at indexes > > + * (ULONG_MAX - N) to ULONG_MAX. It requires nodes to insert single worst-case > > + * item plus extra nodes if you cross the boundary from one node to the next. > > + * > > * Hence: > > */ > > -#define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1) > > +#define RADIX_TREE_PRELOAD_MIN (RADIX_TREE_MAX_PATH * 2 - 1) > > +#define RADIX_TREE_PRELOAD_MAX \ > > + (RADIX_TREE_PRELOAD_MIN + \ > > + DIV_ROUND_UP(RADIX_TREE_PRELOAD_NR - 1, RADIX_TREE_MAP_SIZE)) > Umm, is this really correct? I see two problems: > 1) You may need internal tree nodes at various levels but you seem to > account only for the level 1. > 2) The rounding doesn't seem right because RADIX_TREE_MAP_SIZE+2 nodes may > require 3 nodes at level 1 if the indexes are like: > i_0 | i_1 .. i_{RADIX_TREE_MAP_SIZE} | i_{RADIX_TREE_MAP_SIZE+1} > ^ ^ > node boundary node boundary My bad. Let's try to calculate once again. We want to insert N contiguous items without restriction on alignment. Let's limit N <= 1UL << (2 * RADIX_TREE_MAP_SHIFT), without CONFIG_BASE_SMALL it's 4096. It will simplify calculation a bit. Worst case scenario, I can imagine, is tree with only one element at index 0 and we add N items where at least one index requires max tree high and we cross boundary between items in root node. Basically, at least one index is less then 1UL << ((RADIX_TREE_MAX_PATH - 1) * RADIX_TREE_MAP_SHIFT) and one equal or more. In this case we need: - RADIX_TREE_MAX_PATH nodes to build new path to item with index 0; - DIV_ROUND_UP(N, RADIX_TREE_MAP_SIZE) nodes for last level nodes for new items; - 2 * (RADIX_TREE_MAX_PATH - 2) nodes to build path to last level nodes. (-2, because root node and last level nodes are already accounted). The macro: #define RADIX_TREE_PRELOAD_MAX \ ( RADIX_TREE_MAX_PATH + \ DIV_ROUND_UP(RADIX_TREE_PRELOAD_NR, RADIX_TREE_MAP_SIZE) + \ 2 * (RADIX_TREE_MAX_PATH - 2) ) For 64-bit system and N=512, RADIX_TREE_PRELOAD_MAX is 37. Does it sound correct? Any thoughts? -- Kirill A. Shutemov -- 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