488570ebd4
Many open source projects have moved to using SPDX identifiers to specify license information, reducing the amount of boilerplate code in every source file. This patch replaces the bulk of SPDK .c, .cpp and Makefiles with the BSD-3-Clause identifier. Almost all of these files share the exact same license text, and this patch only modifies the files that contain the most common license text. There can be slight variations because the third clause contains company names - most say "Intel Corporation", but there are instances for Nvidia, Samsung, Eideticom and even "the copyright holder". Used a bash script to automate replacement of the license text with SPDX identifier which is checked into scripts/spdx.sh. Signed-off-by: Jim Harris <james.r.harris@intel.com> Change-Id: Iaa88ab5e92ea471691dc298cfe41ebfb5d169780 Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/12904 Community-CI: Broadcom CI <spdk-ci.pdl@broadcom.com> Community-CI: Mellanox Build Bot Tested-by: SPDK CI Jenkins <sys_sgci@intel.com> Reviewed-by: Aleksey Marchuk <alexeymar@nvidia.com> Reviewed-by: Changpeng Liu <changpeng.liu@intel.com> Reviewed-by: Dong Yi <dongx.yi@intel.com> Reviewed-by: Konrad Sztyber <konrad.sztyber@intel.com> Reviewed-by: Paul Luse <paul.e.luse@intel.com> Reviewed-by: <qun.wan@intel.com>
112 lines
2.4 KiB
C
112 lines
2.4 KiB
C
/* SPDX-License-Identifier: BSD-3-Clause
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* Copyright(c) Intel Corporation. All rights reserved.
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* All rights reserved.
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*/
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#include "spdk/stdinc.h"
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#include "spdk/util.h"
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#include "spdk/zipf.h"
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struct spdk_zipf {
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uint64_t range;
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double alpha;
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double eta;
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double theta;
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double zetan;
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double val1_limit;
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uint32_t seed;
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};
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static double
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zeta_increment(uint64_t n, double theta)
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{
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return pow((double) 1.0 / (n + 1), theta);
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}
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static double
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zeta(uint64_t range, double theta)
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{
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double zetan = 0;
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double inc1, inc2;
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uint64_t i, calc, count;
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const uint32_t ZIPF_MAX_ZETA_CALC = 10 * 1000 * 1000;
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const uint32_t ZIPF_ZETA_ESTIMATE = 1 * 1000 * 1000;
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/* Cumulate zeta discretely for the first ZIPF_MAX_ZETA_CALC
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* entries in the range.
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*/
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calc = spdk_min(ZIPF_MAX_ZETA_CALC, range);
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for (i = 0; i < calc; i++) {
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zetan += zeta_increment(i, theta);
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}
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/* For the remaining values in the range, increment zetan
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* with an approximation for every ZIPF_ZETA_ESTIMATE
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* entries. We will take an average of the increment
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* for (i) and (i + ZIPF_ZETA_ESTIMATE), and then multiply
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* that by ZIPF_ZETA_ESTIMATE.
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*
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* Of course, we'll cap ZIPF_ZETA_ESTIMATE to something
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* smaller if necessary at the end of the range.
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*/
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while (i < range) {
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count = spdk_min(ZIPF_ZETA_ESTIMATE, range - i);
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inc1 = zeta_increment(i, theta);
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inc2 = zeta_increment(i + count, theta);
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zetan += (inc1 + inc2) * count / 2;
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i += count;
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}
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return zetan;
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}
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struct spdk_zipf *
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spdk_zipf_create(uint64_t range, double theta, uint32_t seed)
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{
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struct spdk_zipf *zipf;
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zipf = calloc(1, sizeof(*zipf));
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if (zipf == NULL) {
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return NULL;
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}
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zipf->range = range;
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zipf->seed = seed;
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zipf->theta = theta;
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zipf->alpha = 1.0 / (1.0 - zipf->theta);
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zipf->zetan = zeta(range, theta);
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zipf->eta = (1.0 - pow(2.0 / zipf->range, 1.0 - zipf->theta)) /
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(1.0 - zeta(2, theta) / zipf->zetan);
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zipf->val1_limit = 1.0 + pow(0.5, zipf->theta);
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return zipf;
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}
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void
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spdk_zipf_free(struct spdk_zipf **zipfp)
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{
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assert(zipfp != NULL);
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free(*zipfp);
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*zipfp = NULL;
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}
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uint64_t
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spdk_zipf_generate(struct spdk_zipf *zipf)
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{
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double randu, randz;
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uint64_t val;
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randu = (double)rand_r(&zipf->seed) / RAND_MAX;
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randz = randu * zipf->zetan;
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if (randz < 1.0) {
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return 0;
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} else if (randz < zipf->val1_limit) {
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return 1;
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} else {
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val = zipf->range * pow(zipf->eta * (randu - 1.0) + 1.0, zipf->alpha);
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return val % zipf->range;
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}
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}
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