Messages in this thread | | | Date | Tue, 3 Jul 2018 08:27:23 -0700 | From | Matthew Wilcox <> | Subject | Re: [PATCH v8 03/17] mm: Assign id to every memcg-aware shrinker |
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On Tue, Jul 03, 2018 at 06:09:05PM +0300, Kirill Tkhai wrote: > +++ b/mm/vmscan.c > @@ -169,6 +169,49 @@ unsigned long vm_total_pages; > static LIST_HEAD(shrinker_list); > static DECLARE_RWSEM(shrinker_rwsem); > > +#ifdef CONFIG_MEMCG_KMEM > +static DEFINE_IDR(shrinker_idr); > +static int shrinker_nr_max;
So ... we've now got a list_head (shrinker_list) which contains all of the shrinkers, plus a shrinker_idr which contains the memcg-aware shrinkers?
Why not replace the shrinker_list with the shrinker_idr? It's only used twice in vmscan.c:
void register_shrinker_prepared(struct shrinker *shrinker) { down_write(&shrinker_rwsem); list_add_tail(&shrinker->list, &shrinker_list); up_write(&shrinker_rwsem); }
list_for_each_entry(shrinker, &shrinker_list, list) { ...
The first is simply idr_alloc() and the second is
idr_for_each_entry(&shrinker_idr, shrinker, id) {
I understand there's a difference between allocating the shrinker's ID and adding it to the list. You can do this by calling idr_alloc with NULL as the pointer, and then using idr_replace() when you want to add the shrinker to the list. idr_for_each_entry() skips over NULL entries.
This will actually reduce the size of each shrinker and be more cache-efficient when calling the shrinkers. I think we can also get rid of the shrinker_rwsem eventually, but let's leave it for now.
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