There is two main topics in this patchset. One is to reduce memory usage
and the other is to change a management method of free objects of a slab.
The SLAB allocate a struct slab for each slab. The size of this structure
except bufctl array is 40 bytes on 64 bits machine. We can reduce memory
waste and cache footprint if we overload struct slab over struct page.
And this patchset change a management method of free objects of a slab.
Current free objects management method of the slab is weird, because
it touch random position of the array of kmem_bufctl_t when we try to
get free object. See following example.
struct slab's free = 6
kmem_bufctl_t array: 1 END 5 7 0 4 3 2
To get free objects, we access this array with following pattern.
6 -> 3 -> 7 -> 2 -> 5 -> 4 -> 0 -> 1 -> END
If we have many objects, this array would be larger and be not in the same
cache line. It is not good for performance.
We can do same thing through more easy way, like as the stack.
This patchset implement it and remove complex code for above algorithm.
This makes slab code much cleaner.
This patchset is based on v3.11-rc6, but tested on v3.10.
Thanks.
Joonsoo Kim (16):
slab: correct pfmemalloc check
slab: change return type of kmem_getpages() to struct page
slab: remove colouroff in struct slab
slab: remove nodeid in struct slab
slab: remove cachep in struct slab_rcu
slab: put forward freeing slab management object
slab: overloading the RCU head over the LRU for RCU free
slab: use well-defined macro, virt_to_slab()
slab: use __GFP_COMP flag for allocating slab pages
slab: change the management method of free objects of the slab
slab: remove kmem_bufctl_t
slab: remove SLAB_LIMIT
slab: replace free and inuse in struct slab with newly introduced
active
slab: use struct page for slab management
slab: remove useless statement for checking pfmemalloc
slab: rename slab_bufctl to slab_freelist
include/linux/mm_types.h | 21 +-
include/linux/slab.h | 9 +-
include/linux/slab_def.h | 4 +-
mm/slab.c | 563 ++++++++++++++++++----------------------------
4 files changed, 237 insertions(+), 360 deletions(-)
--
1.7.9.5
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