lkml.org 
[lkml]   [2015]   [May]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCHv5 01/28] mm, proc: adjust PSS calculation
On 05/15/2015 12:56 PM, Kirill A. Shutemov wrote:
> On Thu, May 14, 2015 at 04:12:29PM +0200, Vlastimil Babka wrote:
>> On 04/23/2015 11:03 PM, Kirill A. Shutemov wrote:
>>> With new refcounting all subpages of the compound page are not nessessary
>>> have the same mapcount. We need to take into account mapcount of every
>>> sub-page.
>>>
>>> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
>>> Tested-by: Sasha Levin <sasha.levin@oracle.com>
>>
>> Acked-by: Vlastimil Babka <vbabka@suse.cz>
>>
>> (some nitpicks below)
>>
>>> ---
>>> fs/proc/task_mmu.c | 43 ++++++++++++++++++++++---------------------
>>> 1 file changed, 22 insertions(+), 21 deletions(-)
>>>
>>> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
>>> index 956b75d61809..95bc384ee3f7 100644
>>> --- a/fs/proc/task_mmu.c
>>> +++ b/fs/proc/task_mmu.c
>>> @@ -449,9 +449,10 @@ struct mem_size_stats {
>>> };
>>>
>>> static void smaps_account(struct mem_size_stats *mss, struct page *page,
>>> - unsigned long size, bool young, bool dirty)
>>> + bool compound, bool young, bool dirty)
>>> {
>>> - int mapcount;
>>> + int i, nr = compound ? hpage_nr_pages(page) : 1;
>>
>> Why not just HPAGE_PMD_NR instead of hpage_nr_pages(page)?
>
> Okay, makes sense. Compiler is smart enough to optimize away HPAGE_PMD_NR
> for THP=n. (HPAGE_PMD_NR is BUILD_BUG() for THP=n)

Ah, BUILD_BUG()... I'm not sure we can rely on optimization to avoid
BUILD_BUG(), what if somebody compiles with all optimizations off?
So why not replace BUILD_BUG() with "1", or create a variant of
HPAGE_PMD_NR that does that, for this case and patch 3. Seems better
than testing PageTransHuge everywhere...


\
 
 \ /
  Last update: 2015-05-15 18:21    [W:0.100 / U:0.136 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site