Re: [RFC PATCH 08/12] mm: use mirrorable to switch allocate mirrored memory

[Xishi Qiu <qiuxishi@huawei.com>]

On 2015/6/9 15:06, Kamezawa Hiroyuki wrote:

> On 2015/06/04 22:02, Xishi Qiu wrote:
>> Add a new interface in path /proc/sys/vm/mirrorable. When set to 1, it means
>> we should allocate mirrored memory for both user and kernel processes.
>>
>> Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
> 
> I can't see why do we need this switch. If this is set, all GFP_HIGHUSER will use
> mirrored memory ?
> 
> Or will you add special MMAP/madvise flag to use mirrored memory ?
> 

Hi Kame,

Yes, 

MMAP/madvise 
	-> add VM_MIRROR 
		-> add GFP_MIRROR
			-> use MIGRATE_MIRROR list to alloc mirrored pages

So user can use mirrored memory. What do you think?

Thanks,
Xishi Qiu

> Thanks,
> -Kame
> 
>> ---
>>   include/linux/mmzone.h | 1 +
>>   kernel/sysctl.c        | 9 +++++++++
>>   mm/page_alloc.c        | 1 +
>>   3 files changed, 11 insertions(+)
>>
>> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
>> index f82e3ae..20888dd 100644
>> --- a/include/linux/mmzone.h
>> +++ b/include/linux/mmzone.h
>> @@ -85,6 +85,7 @@ struct mirror_info {
>>   };
>>
>>   extern struct mirror_info mirror_info;
>> +extern int sysctl_mirrorable;
>>   #  define is_migrate_mirror(migratetype) unlikely((migratetype) == MIGRATE_MIRROR)
>>   #else
>>   #  define is_migrate_mirror(migratetype) false
>> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
>> index 2082b1a..dc2625e 100644
>> --- a/kernel/sysctl.c
>> +++ b/kernel/sysctl.c
>> @@ -1514,6 +1514,15 @@ static struct ctl_table vm_table[] = {
>>           .extra2        = &one,
>>       },
>>   #endif
>> +#ifdef CONFIG_MEMORY_MIRROR
>> +    {
>> +        .procname    = "mirrorable",
>> +        .data        = &sysctl_mirrorable,
>> +        .maxlen        = sizeof(sysctl_mirrorable),
>> +        .mode        = 0644,
>> +        .proc_handler    = proc_dointvec_minmax,
>> +    },
>> +#endif
>>       {
>>           .procname    = "user_reserve_kbytes",
>>           .data        = &sysctl_user_reserve_kbytes,
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index 249a8f6..63b90ca 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -212,6 +212,7 @@ int user_min_free_kbytes = -1;
>>
>>   #ifdef CONFIG_MEMORY_MIRROR
>>   struct mirror_info mirror_info;
>> +int sysctl_mirrorable = 0;
>>   #endif
>>
>>   static unsigned long __meminitdata nr_kernel_pages;
>>
> 
> 
> 
> .
> 



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