lkml.org 
[lkml]   [2012]   [Jun]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] mm: setup pageblock_order before it's used by sparse
On Sat, Jun 30, 2012 at 05:07:54PM +0800, Jiang Liu wrote:
> From: Xishi Qiu <qiuxishi@huawei.com>
>
> On architectures with CONFIG_HUGETLB_PAGE_SIZE_VARIABLE set, such as Itanium,
> pageblock_order is a variable with default value of 0. It's set to the right
> value by set_pageblock_order() in function free_area_init_core().
>
> But pageblock_order may be used by sparse_init() before free_area_init_core()
> is called along path:
> sparse_init()
> ->sparse_early_usemaps_alloc_node()
> ->usemap_size()
> ->SECTION_BLOCKFLAGS_BITS
> ->((1UL << (PFN_SECTION_SHIFT - pageblock_order)) *
> NR_PAGEBLOCK_BITS)
>
> The uninitialized pageblock_size will cause memory wasting because usemap_size()
> returns a much bigger value then it's really needed.
>
> For example, on an Itanium platform,
> sparse_init() pageblock_order=0 usemap_size=24576
> free_area_init_core() before pageblock_order=0, usemap_size=24576
> free_area_init_core() after pageblock_order=12, usemap_size=8
>
> That means 24K memory has been wasted for each section, so fix it by calling
> set_pageblock_order() from sparse_init().
>
> Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
> Signed-off-by: Jiang Liu <liuj97@gmail.com>
> ---
> mm/internal.h | 2 ++
> mm/page_alloc.c | 4 ++--
> mm/sparse.c | 3 +++
> 3 files changed, 7 insertions(+), 2 deletions(-)

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read Documentation/stable_kernel_rules.txt
for how to do this properly.

</formletter>


\
 
 \ /
  Last update: 2012-06-30 23:21    [W:0.107 / U:0.120 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site