Subject: Re: [PATCH v3 1/7] Basic kernel memory functionality for the Memory Controller

From: Glauber Costa <[email-masked]>
Date: Mon, 26 Sep 2011 19:44:40 -0300

>>   #endif
>>
>> -
>> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
>> +int do_kmem_account __read_mostly = 1;
>> +#else
>> +#define do_kmem_account		0
>> +#endif
>
>
> Hmm, do we really need this boot option ?
>  From my experience to have swap-accounting boot option,
> this scares us ;) I think config is enough.

If no one else wants it, I can remove it. I personally
don't need it, just wanted to follow the convention laid down by swap here.

>
>
>
>>   /*
>>    * Statistics for memory cgroup.
>>    */
>> @@ -270,6 +274,10 @@ struct mem_cgroup {
>>   	 */
>>   	struct res_counter memsw;
>>   	/*
>> +	 * the counter to account for kmem usage.
>> +	 */
>> +	struct res_counter kmem;
>> +	/*
>>   	 * Per cgroup active and inactive list, similar to the
>>   	 * per zone LRU lists.
>>   	 */
>> @@ -321,6 +329,11 @@ struct mem_cgroup {
>>   	 */
>>   	unsigned long 	move_charge_at_immigrate;
>>   	/*
>> +	 * Should kernel memory limits be stabilished independently
>> +	 * from user memory ?
>> +	 */
>> +	int		kmem_independent;
>> +	/*
>>   	 * percpu counter.
>>   	 */
>>   	struct mem_cgroup_stat_cpu *stat;
>> @@ -388,9 +401,14 @@ enum charge_type {
>>   };
>>
>>   /* for encoding cft->private value on file */
>> -#define _MEM			(0)
>> -#define _MEMSWAP		(1)
>> -#define _OOM_TYPE		(2)
>> +
>> +enum mem_type {
>> +	_MEM = 0,
>> +	_MEMSWAP,
>> +	_OOM_TYPE,
>> +	_KMEM,
>> +};
>> +
>
> ok, nice clean up.
>
>
>>   #define MEMFILE_PRIVATE(x, val)	(((x)<<  16) | (val))
>>   #define MEMFILE_TYPE(val)	(((val)>>  16)&  0xffff)
>>   #define MEMFILE_ATTR(val)	((val)&  0xffff)
>> @@ -3943,10 +3961,15 @@ static inline u64 mem_cgroup_usage(struct mem_cgroup *mem, bool swap)
>>   	u64 val;
>>
>>   	if (!mem_cgroup_is_root(mem)) {
>> +		val = 0;
>> +		if (!mem->kmem_independent)
>> +			val = res_counter_read_u64(&mem->kmem, RES_USAGE);
>
>>   		if (!swap)
>> -			return res_counter_read_u64(&mem->res, RES_USAGE);
>> +			val += res_counter_read_u64(&mem->res, RES_USAGE);
>>   		else
>> -			return res_counter_read_u64(&mem->memsw, RES_USAGE);
>> +			val += res_counter_read_u64(&mem->memsw, RES_USAGE);
>> +
>> +		return val;
>>   	}
>>
>>   	val = mem_cgroup_recursive_stat(mem, MEM_CGROUP_STAT_CACHE);
>> @@ -3979,6 +4002,10 @@ static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
>>   		else
>>   			val = res_counter_read_u64(&mem->memsw, name);
>>   		break;
>> +	case _KMEM:
>> +		val = res_counter_read_u64(&mem->kmem, name);
>> +		break;
>> +
>>   	default:
>>   		BUG();
>>   		break;
>> @@ -4756,6 +4783,21 @@ static int mem_cgroup_reset_vmscan_stat(struct cgroup *cgrp,
>>   	return 0;
>>   }
>>
>> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
>> +static u64 kmem_limit_independent_read(struct cgroup *cont, struct cftype *cft)
>> +{
>> +	return mem_cgroup_from_cont(cont)->kmem_independent;
>> +}
>> +
>> +static int kmem_limit_independent_write(struct cgroup *cont, struct cftype *cft,
>> +					u64 val)
>> +{
>> +	cgroup_lock();
>> +	mem_cgroup_from_cont(cont)->kmem_independent = !!val;
>> +	cgroup_unlock();
>
> Hm. This code allows that parent/child can have different settings.
> Could you add parent-child check as..
>
> "If parent sets use_hierarchy==1, children must have the same kmem_independent value
> with parant's one."
Agree.
> How do you think ? I think a hierarchy must have the same config.
Yes, I think this is reasonable.

>
> BTW...I don't like naming a little ;)
>
> memory->consolidated/shared/?????_kmem_accounting ?
> Or
> memory->kmem_independent_accounting ?
>
> or some better naming ?

I can go with kmem_independent_accounting if you like, it is fine
by me.

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