On Fri, Feb 08 2013, Glauber Costa wrote:
> When a new memcg is created, we need to open up room for its descriptors
> in all of the list_lrus that are marked per-memcg. The process is quite
> similar to the one we are using for the kmem caches: we initialize the
> new structures in an array indexed by kmemcg_id, and grow the array if
> needed. Key data like the size of the array will be shared between the
> kmem cache code and the list_lru code (they basically describe the same
> thing)
>
> Signed-off-by: Glauber Costa <glommer@xxxxxxxxxxxxx>
> Cc: Dave Chinner <dchinner@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
> include/linux/list_lru.h | 47 +++++++++++++++++
> include/linux/memcontrol.h | 6 +++
> lib/list_lru.c | 115 +++++++++++++++++++++++++++++++++++++---
> mm/memcontrol.c | 128 ++++++++++++++++++++++++++++++++++++++++++---
> mm/slab_common.c | 1 -
> 5 files changed, 283 insertions(+), 14 deletions(-)
>
> diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h
> index 02796da..370b989 100644
> --- a/include/linux/list_lru.h
> +++ b/include/linux/list_lru.h
> @@ -16,11 +16,58 @@ struct list_lru_node {
> long nr_items;
> } ____cacheline_aligned_in_smp;
>
> +struct list_lru_array {
> + struct list_lru_node node[1];
> +};
> +
> struct list_lru {
> + struct list_head lrus;
> struct list_lru_node node[MAX_NUMNODES];
> nodemask_t active_nodes;
> +#ifdef CONFIG_MEMCG_KMEM
> + struct list_lru_array **memcg_lrus;
Probably need a comment regarding that 0x1 is a magic value and
describing what indexes this lazily constructed array. Is the primary
index memcg_kmem_id and the secondary index a nid?
> +#endif
> };
>
> +struct mem_cgroup;
> +#ifdef CONFIG_MEMCG_KMEM
> +/*
> + * We will reuse the last bit of the pointer to tell the lru subsystem that
> + * this particular lru should be replicated when a memcg comes in.
> + */
>From this patch it seems like 0x1 is a magic value rather than bit 0
being special. memcg_lrus is either 0x1 or a pointer to an array of
struct list_lru_array. The array is indexed by memcg_kmem_id.
> +static inline void lru_memcg_enable(struct list_lru *lru)
This function is not called yet. Hmm.
> +{
> + lru->memcg_lrus = (void *)0x1ULL;
> +}
> +
> +/*
> + * This will return true if we have already allocated and assignment a memcg
> + * pointer set to the LRU. Therefore, we need to mask the first bit out
> + */
> +static inline bool lru_memcg_is_assigned(struct list_lru *lru)
> +{
> + return (unsigned long)lru->memcg_lrus & ~0x1ULL;
Is this equivalent to?
return lru->memcg_lrus != NULL && lru->memcg_lrus != 0x1
> +}
> +
[...]
/* comment the meaning of "num" */
> +int memcg_update_all_lrus(unsigned long num)
> +{
> + int ret = 0;
> + struct list_lru *lru;
> +
[...]
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