Re: [PATCH v3] mm/slab: Improve performance of gathering slabinfo stats
From: Aruna Ramakrishna
Date: Wed Aug 17 2016 - 15:25:53 EST
On 08/17/2016 12:03 PM, Eric Dumazet wrote:
On Wed, 2016-08-17 at 11:20 -0700, Aruna Ramakrishna wrote:
]
- list_for_each_entry(page, &n->slabs_full, lru) {
- if (page->active != cachep->num && !error)
- error = "slabs_full accounting error";
- active_objs += cachep->num;
- active_slabs++;
- }
Since you only removed this loop, you could track only number of
full_slabs.
This would avoid messing with n->num_slabs all over the places in fast
path.
Please also update slab_out_of_memory()
Eric,
Right now, n->num_slabs is modified only when a slab is detached from
slabs_free (i.e. in drain_freelist and free_block) or when a new one is
attached in cache_grow_end. None of those 3 calls are in the fast path,
right? Tracking just full_slabs would also involve similar changes:
decrement when a slab moves from full to partial during free_block, and
increment when it moves from partial/free to full after allocation in
fixup_slab_list. So I don't see what the real difference/advantage is.
I will update slab_out_of_memory and remove the slabs_full list
traversal there too.
Thanks,
Aruna