From 8348daf915d4b2c3ec95a16ad803e9e42eb2bfda Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@fb.com>
Date: Mon, 16 May 2016 18:09:43 -0600
Subject: [PATCH] zipf/pareto/gauss: add option to disable hashing

Signed-off-by: Jens Axboe <axboe@fb.com>
---
 lib/gauss.c | 10 +++++++++-
 lib/gauss.h |  2 ++
 lib/zipf.c  | 15 +++++++++++++--
 lib/zipf.h  |  2 ++
 4 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/lib/gauss.c b/lib/gauss.c
index afd0490d..48e2fbfe 100644
--- a/lib/gauss.c
+++ b/lib/gauss.c
@@ -38,7 +38,10 @@ unsigned long long gauss_next(struct gauss_state *gs)
 		sum += dev;
 	}
 
-	return __hash_u64(sum) % gs->nranges;
+	if (!gs->disable_hash)
+		return __hash_u64(sum) % gs->nranges;
+
+	return sum % gs->nranges;
 }
 
 void gauss_init(struct gauss_state *gs, unsigned long nranges, double dev,
@@ -54,3 +57,8 @@ void gauss_init(struct gauss_state *gs, unsigned long nranges, double dev,
 			gs->stddev = nranges / 2;
 	}
 }
+
+void gauss_disable_hash(struct gauss_state *gs)
+{
+	gs->disable_hash = true;
+}
diff --git a/lib/gauss.h b/lib/gauss.h
index a76df3f2..478aa146 100644
--- a/lib/gauss.h
+++ b/lib/gauss.h
@@ -8,10 +8,12 @@ struct gauss_state {
 	struct frand_state r;
 	uint64_t nranges;
 	unsigned int stddev;
+	bool disable_hash;
 };
 
 void gauss_init(struct gauss_state *gs, unsigned long nranges, double dev,
 		unsigned int seed);
 unsigned long long gauss_next(struct gauss_state *gs);
+void gauss_disable_hash(struct gauss_state *gs);
 
 #endif
diff --git a/lib/zipf.c b/lib/zipf.c
index d8e72b15..8b581faf 100644
--- a/lib/zipf.c
+++ b/lib/zipf.c
@@ -69,7 +69,10 @@ 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_u64(val - 1) + zs->rand_off) % zs->nranges;
+	if (!zs->disable_hash)
+		return (__hash_u64(val - 1) + zs->rand_off) % zs->nranges;
+
+	return (val - 1 + zs->rand_off) % zs->nranges;
 }
 
 void pareto_init(struct zipf_state *zs, unsigned long nranges, double h,
@@ -84,5 +87,13 @@ unsigned long long pareto_next(struct zipf_state *zs)
 	double rand = (double) __rand(&zs->rand) / (double) FRAND32_MAX;
 	unsigned long long n = zs->nranges - 1;
 
-	return (__hash_u64(n * pow(rand, zs->pareto_pow)) + zs->rand_off) % zs->nranges;
+	if (!zs->disable_hash)
+		return (__hash_u64(n * pow(rand, zs->pareto_pow)) + zs->rand_off) % zs->nranges;
+
+	return (unsigned long long) (n * pow(rand, zs->pareto_pow) + zs->rand_off) % zs->nranges;
+}
+
+void zipf_disable_hash(struct zipf_state *zs)
+{
+	zs->disable_hash = true;
 }
diff --git a/lib/zipf.h b/lib/zipf.h
index f98ad818..af2d0e64 100644
--- a/lib/zipf.h
+++ b/lib/zipf.h
@@ -12,6 +12,7 @@ struct zipf_state {
 	double pareto_pow;
 	struct frand_state rand;
 	uint64_t rand_off;
+	bool disable_hash;
 };
 
 void zipf_init(struct zipf_state *zs, unsigned long nranges, double theta, unsigned int seed);
@@ -19,5 +20,6 @@ unsigned long long zipf_next(struct zipf_state *zs);
 
 void pareto_init(struct zipf_state *zs, unsigned long nranges, double h, unsigned int seed);
 unsigned long long pareto_next(struct zipf_state *zs);
+void zipf_disable_hash(struct zipf_state *zs);
 
 #endif
-- 
2.25.1