Home » Mailing lists » Devel » [PATCH v3 00/28] kmem limitation for memcg
| Re: [PATCH v3 12/28] slab: pass memcg parameter to kmem_cache_create [message #46573 is a reply to message #46564] |
Tue, 29 May 2012 15:50   |
Glauber Costa
Messages: 916
Registered: October 2011
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Senior Member |
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On 05/29/2012 06:27 PM, Christoph Lameter wrote:
> On Fri, 25 May 2012, Glauber Costa wrote:
>
>> index 06e4a3e..7c0cdd6 100644
>> --- a/include/linux/slab_def.h
>> +++ b/include/linux/slab_def.h
>> @@ -102,6 +102,13 @@ struct kmem_cache {
>> */
>> };
>>
>> +static inline void store_orig_align(struct kmem_cache *cachep, int orig_align)
>> +{
>> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
>> + cachep->memcg_params.orig_align = orig_align;
>> +#endif
>> +}
>> +
>
> Why do you need to store the original alignment? Is the calculated
> alignment not enough?
I think this one can go. You are right.
>> +++ b/mm/slab.c
>> @@ -1729,6 +1729,31 @@ void __init kmem_cache_init_late(void)
>> */
>> }
>>
>> +static int __init memcg_slab_register_all(void)
>> +{
>> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
>> + struct kmem_cache *cachep;
>> + struct cache_sizes *sizes;
>> +
>> + sizes = malloc_sizes;
>> +
>> + while (sizes->cs_size != ULONG_MAX) {
>> + if (sizes->cs_cachep)
>> + mem_cgroup_register_cache(NULL, sizes->cs_cachep);
>> + if (sizes->cs_dmacachep)
>> + mem_cgroup_register_cache(NULL, sizes->cs_dmacachep);
>> + sizes++;
>> + }
>> +
>> + mutex_lock(&cache_chain_mutex);
>> + list_for_each_entry(cachep,&cache_chain, next)
>> + mem_cgroup_register_cache(NULL, cachep);
>> +
>> + mutex_unlock(&cache_chain_mutex);
>> +#endif /* CONFIG_CGROUP_MEM_RES_CTLR_KMEM */
>> + return 0;
>> +}
>
> Ok this only duplicates the kmalloc arrays. Why not the others?
It does duplicate the others.
First it does a while look on the kmalloc caches, then a
list_for_each_entry in the rest. You probably missed it.
>> @@ -2331,7 +2350,7 @@ kmem_cache_create (const char *name, size_t size, size_t align,
>> continue;
>> }
>>
>> - if (!strcmp(pc->name, name)) {
>> + if (!memcg&& !strcmp(pc->name, name)) {
>> printk(KERN_ERR
>> "kmem_cache_create: duplicate cache %s\n", name);
>> dump_stack();
>
> This implementation means that duplicate cache detection will no longer
> work within a cgroup?
For the slab, yes. For the slub, I check to see if they belong to the
same memcg.
That said, this can and should be fixed here too, thanks for spotting.
>> @@ -2543,7 +2564,12 @@ kmem_cache_create (const char *name, size_t size, size_t align,
>> cachep->ctor = ctor;
>> cachep->name = name;
>>
>> + if (g_cpucache_up>= FULL)
>> + mem_cgroup_register_cache(memcg, cachep);
>
> What happens if a cgroup was active during creation of slab xxy but
> then a process running in a different cgroup uses that slab to allocate
> memory? Is it charged to the first cgroup?
I don't see this situation ever happening. kmem_cache_create, when
called directly, will always create a global cache. It doesn't matter
which cgroups are or aren't active at this time or any other. We create
copies per-cgroup, but we create it lazily, when someone will touch it.
At that point, which cache will be used depend on which process is using
it.
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