diff options
Diffstat (limited to 'src/mpmc_ring.h')
| -rw-r--r-- | src/mpmc_ring.h | 49 |
1 files changed, 25 insertions, 24 deletions
diff --git a/src/mpmc_ring.h b/src/mpmc_ring.h index 32f6048..4a0f55b 100644 --- a/src/mpmc_ring.h +++ b/src/mpmc_ring.h @@ -35,16 +35,13 @@ #define CK_CC_FORCE_INLINE __always_inline #endif -#ifndef CK_MD_CACHELINE -#define CK_MD_CACHELINE (64) -#endif - #include <stdbool.h> #include <linux/string.h> #include <linux/processor.h> #include <linux/compiler.h> #include <linux/atomic.h> +#include <linux/cache.h> //#define likely(x) (__builtin_expect(!!(x), 1)) //#define unlikely(x) (__builtin_expect(!!(x), 0)) //#define cpu_relax() @@ -52,7 +49,7 @@ //#define ck_pr_load_uint(SRC) CK_PR_LOAD_SAFE((SRC), uint) /* http://concurrencykit.org/doc/ck_pr_load.html */ -#define ck_pr_load_uint(SRC) READ_ONCE(*(SRC)) +#define ck_pr_load_uint(SRC) atomic_read(SRC) /* http://concurrencykit.org/doc/ck_pr_fence_load.html */ #define ck_pr_fence_load() smp_rmb() @@ -64,14 +61,26 @@ #define ck_pr_stall() cpu_relax() /* http://concurrencykit.org/doc/ck_pr_fence_store_atomic.html */ -#define ck_pr_fence_store_atomic() +/* this actually resolves to __asm__ __volatile__("" ::: "memory"); in x86-64 */ +/* so basically a compiler barrier? */ +#define ck_pr_fence_store_atomic() smp_mb__before_atomic() /* TODO: probably overkill? */ /* http://concurrencykit.org/doc/ck_pr_cas.html */ -#define ck_pr_cas_uint_value(A, B, C, D) 1 +/* + ck_pr_cas_uint_value(unsigned int *target, unsigned int compare, + unsigned int set, unsigned int *v) { + _Bool + z; __asm__ __volatile__("lock " "cmpxchg" "l" " %3, %0;" "mov %% " "eax" ", %2;" "setz %1;" : "+m" (*(unsigned int *)target), "=a" (z), "=m" (*(unsigned int *)v) : "q" (set), "a" (compare) : "memory", "cc"); + return z; } +*/ +bool ck_pr_cas_uint_value(atomic_t *target, uint old, uint new, uint *v) { + uint prev = atomic_cmpxchg(target, old, new); + *v = new; + return prev != old; +} /* http://concurrencykit.org/doc/ck_pr_cas.html */ -// long cas(long *mem, long old, long new); -#define ck_pr_cas_uint(t, old, new) atomic_cmpxchg(t, old, new) +#define ck_pr_cas_uint(t, old, new) atomic_cmpxchg(t, old, new) != old /* http://concurrencykit.org/doc/ck_pr_store.html */ // TODO: compiler barrier? @@ -82,15 +91,11 @@ */ struct ck_ring { - //unsigned int c_head; - atomic_t c_head; - /* TODO: use ____cacheline_aligned_in_smp or someting like that */ - char pad[CK_MD_CACHELINE - sizeof(unsigned int)]; - unsigned int p_tail; - //unsigned int p_head; + /* TODO: is the aligment correct? */ + atomic_t c_head ____cacheline_aligned_in_smp; + atomic_t p_tail ____cacheline_aligned_in_smp; atomic_t p_head; - char _pad[CK_MD_CACHELINE - sizeof(unsigned int) * 2]; - unsigned int size; + unsigned int size ____cacheline_aligned_in_smp; unsigned int mask; }; typedef struct ck_ring ck_ring_t; @@ -103,10 +108,9 @@ typedef struct ck_ring_buffer ck_ring_buffer_t; CK_CC_INLINE static void ck_ring_init(struct ck_ring *ring, unsigned int size) { - ring->size = size; ring->mask = size - 1; - ring->p_tail = 0; + atomic_set(&ring->p_tail, 0); atomic_set(&ring->p_head, 0); // TODO: barrier? atomic_set(&ring->c_head, 0); return; @@ -220,16 +224,13 @@ _ck_ring_trydequeue_mc(struct ck_ring *ring, unsigned int size) { const unsigned int mask = ring->mask; - //unsigned int consumer, producer; - unsigned int producer; - atomic_t consumer; + unsigned int consumer, producer; consumer = ck_pr_load_uint(&ring->c_head); ck_pr_fence_load(); producer = ck_pr_load_uint(&ring->p_tail); - if (unlikely(atomic_read(&consumer) == producer)) - //if (unlikely(consumer == producer)) + if (unlikely(consumer == producer)) return false; ck_pr_fence_load(); |