Hi,
On Wed, Sep 09, 2015 at 12:01:46AM +0530, Raghavendra K T wrote:
> The functions used in the patch are in slowpath, which gets called
> whenever alloc_super is called during mounts.
>
> Though this should not make difference for the architectures with
> sequential numa node ids, for the powerpc which can potentially have
> sparse node ids (for e.g., 4 node system having numa ids, 0,1,16,17
> is common), this patch saves some unnecessary allocations for
> non existing numa nodes.
>
> Even without that saving, perhaps patch makes code more readable.
Do I understand correctly that node 0 must always be in
node_possible_map? I ask, because we currently test
lru->node[0].memcg_lrus to determine if the list is memcg aware.
>
> Signed-off-by: Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>
> ---
> mm/list_lru.c | 23 +++++++++++++++--------
> 1 file changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/mm/list_lru.c b/mm/list_lru.c
> index 909eca2..5a97f83 100644
> --- a/mm/list_lru.c
> +++ b/mm/list_lru.c
> @@ -377,7 +377,7 @@ static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
> {
> int i;
>
> - for (i = 0; i < nr_node_ids; i++) {
> + for_each_node(i) {
> if (!memcg_aware)
> lru->node[i].memcg_lrus = NULL;
So, we don't explicitly initialize memcg_lrus for nodes that are not in
node_possible_map. That's OK, because we allocate lru->node using
kzalloc. However, this partial nullifying in case !memcg_aware looks
confusing IMO. Let's drop it, I mean something like this:
static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
{
int i;
if (!memcg_aware)
return 0;
for_each_node(i) {
if (memcg_init_list_lru_node(&lru->node[i]))
goto fail;
}
Thanks,
Vladimir
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