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SubjectRe: [RFC PATCH 10/12] mm: add the buddy system interface
On 2015/06/25 18:44, Xishi Qiu wrote:
> On 2015/6/10 11:06, Kamezawa Hiroyuki wrote:
>
>> On 2015/06/09 19:04, Xishi Qiu wrote:
>>> On 2015/6/9 15:12, Kamezawa Hiroyuki wrote:
>>>
>>>> On 2015/06/04 22:04, Xishi Qiu wrote:
>>>>> Add the buddy system interface for address range mirroring feature.
>>>>> Allocate mirrored pages in MIGRATE_MIRROR list. If there is no mirrored pages
>>>>> left, use other types pages.
>>>>>
>>>>> Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
>>>>> ---
>>>>> mm/page_alloc.c | 40 +++++++++++++++++++++++++++++++++++++++-
>>>>> 1 file changed, 39 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>>>>> index d4d2066..0fb55288 100644
>>>>> --- a/mm/page_alloc.c
>>>>> +++ b/mm/page_alloc.c
>>>>> @@ -599,6 +599,26 @@ static inline bool is_mirror_pfn(unsigned long pfn)
>>>>>
>>>>> return false;
>>>>> }
>>>>> +
>>>>> +static inline bool change_to_mirror(gfp_t gfp_flags, int high_zoneidx)
>>>>> +{
>>>>> + /*
>>>>> + * Do not alloc mirrored memory below 4G, because 0-4G is
>>>>> + * all mirrored by default, and the list is always empty.
>>>>> + */
>>>>> + if (high_zoneidx < ZONE_NORMAL)
>>>>> + return false;
>>>>> +
>>>>> + /* Alloc mirrored memory for only kernel */
>>>>> + if (gfp_flags & __GFP_MIRROR)
>>>>> + return true;
>>>>
>>>> GFP_KERNEL itself should imply mirror, I think.
>>>>
>>>
>>> Hi Kame,
>>>
>>> How about like this: #define GFP_KERNEL (__GFP_WAIT | __GFP_IO | __GFP_FS | __GFP_MIRROR) ?
>>>
>>
>> Hm.... it cannot cover GFP_ATOMIC at el.
>>
>> I guess, mirrored memory should be allocated if !__GFP_HIGHMEM or !__GFP_MOVABLE
>
>
> Hi Kame,
>
> Can we distinguish allocations form user or kernel only by GFP flags?
>

Allocation from user and file caches are now *always* done with __GFP_MOVABLE.

By this, pages will be allocated from MIGRATE_MOVABLE migration type.
MOVABLE migration type means it's can
be the target for page compaction or memory-hot-remove.

Thanks,
-Kame









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