Re: [PATCH 1/7] vmscan: also shrink slab in memcg pressure

[Glauber Costa <glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>]

>> @@ -45,6 +48,7 @@ struct shrinker {
>>   
>>   	int seeks;	/* seeks to recreate an obj */
>>   	long batch;	/* reclaim batch size, 0 = default */
>> +	bool memcg_shrinker;
>>   
> 
> What is this boolean for ? When is this set ?
It is set when a subsystem declares that its shrinker is memcg capable.
Therefore, it won't be done until all infrastructure is in place. Take a
look at the super.c patches at the end of the series.


>>   static bool global_reclaim(struct scan_control *sc)
>>   {
>>   	return true;
>>   }
>> +
>> +static bool has_kmem_reclaim(struct scan_control *sc)
>> +{
>> +	return true;
>> +}
>> +
>> +static unsigned long
>> +zone_nr_reclaimable_pages(struct scan_control *sc, struct zone *zone)
>> +{
>> +	return zone_reclaimable_pages(zone);
>> +}
>>   #endif
> 
> Can't be in a devided patch ?
> 
if you prefer this way, sure, I can separate it.

>>   static unsigned long get_lru_size(struct lruvec *lruvec, enum lru_list lru)
>> @@ -221,6 +252,9 @@ unsigned long shrink_slab(struct shrink_control *sc,
>>   		long batch_size = shrinker->batch ? shrinker->batch
>>   						  : SHRINK_BATCH;
>>   
>> +		if (!shrinker->memcg_shrinker && sc->target_mem_cgroup)
>> +			continue;
>> +
> 
> What does this mean ?

It means that if target_mem_cgroup is set, we should skip all the
shrinkers that are not memcg capable. Maybe if I invert the order it
will be clearer?