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authorJens Axboe <axboe@kernel.dk>2012-11-11 08:27:24 +0100
committerJens Axboe <axboe@kernel.dk>2012-11-11 08:27:24 +0100
commita5a4fdfd44ec1b55ebab7800a931c148540a7324 (patch)
treefd83eb6acf4d06319dec5517dc2ea55a184ce31a
parent921d17ba00f6fa106f558ea285d1d503f3a41369 (diff)
downloadfio-a5a4fdfd44ec1b55ebab7800a931c148540a7324.tar.gz
fio-a5a4fdfd44ec1b55ebab7800a931c148540a7324.tar.bz2
zipf: use 64-bit safe hash for zipf/pareto
Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--hash.h7
-rw-r--r--lib/zipf.c4
-rw-r--r--lib/zipf.h2
3 files changed, 10 insertions, 3 deletions
diff --git a/hash.h b/hash.h
index 93dd8318..13600f4e 100644
--- a/hash.h
+++ b/hash.h
@@ -28,6 +28,8 @@
#error Define GOLDEN_RATIO_PRIME for your wordsize.
#endif
+#define GR_PRIME_64 0x9e37fffffffc0001UL
+
static inline unsigned long __hash_long(unsigned long val)
{
unsigned long hash = val;
@@ -60,6 +62,11 @@ static inline unsigned long hash_long(unsigned long val, unsigned int bits)
/* High bits are more random, so use them. */
return __hash_long(val) >> (BITS_PER_LONG - bits);
}
+
+static inline uint64_t __hash_u64(uint64_t val)
+{
+ return val * GR_PRIME_64;
+}
static inline unsigned long hash_ptr(void *ptr, unsigned int bits)
{
diff --git a/lib/zipf.c b/lib/zipf.c
index 41e20554..9b6ce633 100644
--- a/lib/zipf.c
+++ b/lib/zipf.c
@@ -69,7 +69,7 @@ unsigned long long zipf_next(struct zipf_state *zs)
else
val = 1 + (unsigned long long)(n * pow(eta*rand_uni - eta + 1.0, alpha));
- return (__hash_long(val - 1) + zs->rand_off) % zs->nranges;
+ return (__hash_u64(val - 1) + zs->rand_off) % zs->nranges;
}
void pareto_init(struct zipf_state *zs, unsigned long nranges, double h,
@@ -84,5 +84,5 @@ unsigned long long pareto_next(struct zipf_state *zs)
double rand = (double) __rand(&zs->rand) / (double) FRAND_MAX;
unsigned long long n = zs->nranges - 1;
- return (__hash_long(n * pow(rand, zs->pareto_pow)) + zs->rand_off) % zs->nranges;
+ return (__hash_u64(n * pow(rand, zs->pareto_pow)) + zs->rand_off) % zs->nranges;
}
diff --git a/lib/zipf.h b/lib/zipf.h
index dbcaffb2..f98ad818 100644
--- a/lib/zipf.h
+++ b/lib/zipf.h
@@ -11,7 +11,7 @@ struct zipf_state {
double zetan;
double pareto_pow;
struct frand_state rand;
- unsigned long rand_off;
+ uint64_t rand_off;
};
void zipf_init(struct zipf_state *zs, unsigned long nranges, double theta, unsigned int seed);