Justus Winter, le Mon 06 Jan 2014 00:34:55 +0100, a écrit :
> * kern/slab.h (struct kmem_cache): Reorder the fields so that all hot
> fields are within the first cache line.
Did you try to benchmark this a bit?
I'm unsure about all movements: nr_free_slabs, for instance, should
probably really go along nr_slabs, as well as nr_objs, etc.
> ---
> kern/slab.h | 18 ++++++++++++------
> 1 file changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/kern/slab.h b/kern/slab.h
> index fd65893..457dee4 100644
> --- a/kern/slab.h
> +++ b/kern/slab.h
> @@ -157,6 +157,10 @@ typedef void (*kmem_slab_free_fn_t)(vm_offset_t,
> vm_size_t);
> * Cache of objects.
> *
> * Locking order : cpu_pool -> cache. CPU pools locking is ordered by CPU ID.
> + *
> + * Currently, SLAB_USE_CPU_POOLS is not defined. KMEM_CACHE_NAME_SIZE
> + * is chosen so that the struct fits into two cache lines. The first
> + * cache line contains all hot fields.
> */
> struct kmem_cache {
> #if SLAB_USE_CPU_POOLS
> @@ -172,19 +176,21 @@ struct kmem_cache {
> struct list free_slabs;
> struct rbtree active_slabs;
> int flags;
> + size_t bufctl_dist; /* Distance from buffer to bufctl */
> + size_t slab_size;
> + unsigned long bufs_per_slab;
> + unsigned long nr_objs; /* Number of allocated objects */
> + unsigned long nr_free_slabs;
> + kmem_cache_ctor_t ctor;
> + /* All fields below are cold */
> size_t obj_size; /* User-provided size */
> + /* Assuming ! SLAB_USE_CPU_POOLS, here is the cacheline boundary */
> size_t align;
> size_t buf_size; /* Aligned object size */
> - size_t bufctl_dist; /* Distance from buffer to bufctl */
> - size_t slab_size;
> size_t color;
> size_t color_max;
> - unsigned long bufs_per_slab;
> - unsigned long nr_objs; /* Number of allocated objects */
> unsigned long nr_bufs; /* Total number of buffers */
> unsigned long nr_slabs;
> - unsigned long nr_free_slabs;
> - kmem_cache_ctor_t ctor;
> kmem_slab_alloc_fn_t slab_alloc_fn;
> kmem_slab_free_fn_t slab_free_fn;
> char name[KMEM_CACHE_NAME_SIZE];
> --
> 1.8.5.2
>
--
Samuel
<N> (* If you have a precise idea of the intended use of the following code,
please
<N> write to eduardo.gime...@inria.fr and ask for the prize :-)
<N> -- Eduardo (11/8/97) *)
-+- N sur #ens-mim - et c'était un des développeurs -+-
