util: add zipf random number generator (199fa601) · Commits · Public Repositories / spdk

include/spdk/stdinc.h

+1 −0

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		@@ -50,6 +50,7 @@ extern "C" {
		#include <errno.h>
		#include <inttypes.h>
		#include <limits.h>
		#include <math.h>
		#include <stdarg.h>
		#include <stdbool.h>
		#include <stddef.h>

include/spdk/zipf.h

0 → 100644

+83 −0

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		/*-
		* BSD LICENSE
		*
		* Copyright (c) Intel Corporation.
		* All rights reserved.
		*
		* Redistribution and use in source and binary forms, with or without
		* modification, are permitted provided that the following conditions
		* are met:
		*
		* * Redistributions of source code must retain the above copyright
		* notice, this list of conditions and the following disclaimer.
		* * Redistributions in binary form must reproduce the above copyright
		* notice, this list of conditions and the following disclaimer in
		* the documentation and/or other materials provided with the
		* distribution.
		* * Neither the name of Intel Corporation nor the names of its
		* contributors may be used to endorse or promote products derived
		* from this software without specific prior written permission.
		*
		* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
		* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
		* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
		* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
		* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
		* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
		* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
		* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
		* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
		* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
		* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
		*/

		/** \file
		* Zipf random number distribution
		*/

		#ifndef SPDK_ZIPF_H
		#define SPDK_ZIPF_H

		#include "spdk/stdinc.h"

		#ifdef __cplusplus
		extern "C" {
		#endif

		struct spdk_zipf;

		/**
		* Create a zipf random number generator.
		*
		* Numbers from [0, range) will be returned by the generator when
		* calling \ref spdk_zipf_generate.
		*
		* \param range Range of values for the zipf distribution.
		* \param theta Theta distribution parameter.
		* \param seed Seed value for the random number generator.
		*
		* \return a pointer to the new zipf generator.
		*/
		struct spdk_zipf *spdk_zipf_create(uint64_t range, double theta, uint32_t seed);

		/**
		* Free a zipf generator and set the pointer to NULL.
		*
		* \param zipfp Zipf generator to free.
		*/
		void spdk_zipf_free(struct spdk_zipf **zipfp);

		/**
		* Generate a value from the zipf generator.
		*
		* \param zipf Zipf generator to generate the value from.
		*
		* \return value in the range [0, range)
		*/
		uint64_t spdk_zipf_generate(struct spdk_zipf *zipf);

		#ifdef __cplusplus
		}
		#endif

		#endif

lib/util/Makefile

+2 −2

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		@@ -35,11 +35,11 @@ SPDK_ROOT_DIR := $(abspath $(CURDIR)/../..)
		include $(SPDK_ROOT_DIR)/mk/spdk.common.mk

		SO_VER := 3
		SO_MINOR := 0
		SO_MINOR := 1

		C_SRCS = base64.c bit_array.c cpuset.c crc16.c crc32.c crc32c.c crc32_ieee.c \
		dif.c fd.c file.c iov.c math.c pipe.c strerror_tls.c string.c uuid.c \
		fd_group.c
		fd_group.c zipf.c
		LIBNAME = util
		LOCAL_SYS_LIBS = -luuid

lib/util/spdk_util.map

+5 −0

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		@@ -144,5 +144,10 @@
		spdk_fd_group_event_modify;
		spdk_fd_group_get_fd;

		# public functions in zipf.h
		spdk_zipf_create;
		spdk_zipf_free;
		spdk_zipf_generate;

		local: *;
		};

lib/util/zipf.c

0 → 100644

+139 −0

Original line number	Diff line number	Diff line
		/*-
		* BSD LICENSE
		*
		* Copyright(c) Intel Corporation. All rights reserved.
		* All rights reserved.
		*
		* Redistribution and use in source and binary forms, with or without
		* modification, are permitted provided that the following conditions
		* are met:
		*
		* * Redistributions of source code must retain the above copyright
		* notice, this list of conditions and the following disclaimer.
		* * Redistributions in binary form must reproduce the above copyright
		* notice, this list of conditions and the following disclaimer in
		* the documentation and/or other materials provided with the
		* distribution.
		* * Neither the name of Intel Corporation nor the names of its
		* contributors may be used to endorse or promote products derived
		* from this software without specific prior written permission.
		*
		* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
		* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
		* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
		* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
		* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
		* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
		* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
		* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
		* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
		* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
		* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
		*/

		#include "spdk/stdinc.h"
		#include "spdk/util.h"
		#include "spdk/zipf.h"

		struct spdk_zipf {
		uint64_t range;
		double alpha;
		double eta;
		double theta;
		double zetan;
		double val1_limit;
		uint32_t seed;
		};

		static double
		zeta_increment(uint64_t n, double theta)
		{
		return pow((double) 1.0 / (n + 1), theta);
		}

		static double
		zeta(uint64_t range, double theta)
		{
		double zetan = 0;
		double inc1, inc2;
		uint64_t i, calc, count;
		const uint32_t ZIPF_MAX_ZETA_CALC = 10 * 1000 * 1000;
		const uint32_t ZIPF_ZETA_ESTIMATE = 1 * 1000 * 1000;

		/* Cumulate zeta discretely for the first ZIPF_MAX_ZETA_CALC
		* entries in the range.
		*/
		calc = spdk_min(ZIPF_MAX_ZETA_CALC, range);
		for (i = 0; i < calc; i++) {
		zetan += zeta_increment(i, theta);
		}

		/* For the remaining values in the range, increment zetan
		* with an approximation for every ZIPF_ZETA_ESTIMATE
		* entries. We will take an average of the increment
		* for (i) and (i + ZIPF_ZETA_ESTIMATE), and then multiply
		* that by ZIPF_ZETA_ESTIMATE.
		*
		* Of course, we'll cap ZIPF_ZETA_ESTIMATE to something
		* smaller if necessary at the end of the range.
		*/
		while (i < range) {
		count = spdk_min(ZIPF_ZETA_ESTIMATE, range - i);
		inc1 = zeta_increment(i, theta);
		inc2 = zeta_increment(i + count, theta);
		zetan += (inc1 + inc2) * count / 2;
		i += count;
		}

		return zetan;
		}

		struct spdk_zipf *
		spdk_zipf_create(uint64_t range, double theta, uint32_t seed)
		{
		struct spdk_zipf *zipf;

		zipf = calloc(1, sizeof(*zipf));
		if (zipf == NULL) {
		return NULL;
		}

		zipf->range = range;
		zipf->seed = seed;

		zipf->theta = theta;
		zipf->alpha = 1.0 / (1.0 - zipf->theta);
		zipf->zetan = zeta(range, theta);
		zipf->eta = (1.0 - pow(2.0 / zipf->range, 1.0 - zipf->theta)) /
		(1.0 - zeta(2, theta) / zipf->zetan);
		zipf->val1_limit = 1.0 + pow(0.5, zipf->theta);

		return zipf;
		}

		void
		spdk_zipf_free(struct spdk_zipf **zipfp)
		{
		assert(zipfp != NULL);
		free(*zipfp);
		*zipfp = NULL;
		}

		uint64_t
		spdk_zipf_generate(struct spdk_zipf *zipf)
		{
		double randu, randz;
		uint64_t val;

		randu = (double)rand_r(&zipf->seed) / RAND_MAX;
		randz = randu * zipf->zetan;

		if (randz < 1.0) {
		return 0;
		} else if (randz < zipf->val1_limit) {
		return 1;
		} else {
		val = zipf->range * pow(zipf->eta * (randu - 1.0) + 1.0, zipf->alpha);
		return val % zipf->range;
		}
		}

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