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[204.195.112.199]) by smtp.gmail.com with ESMTPSA id j64-20020a62c543000000b0050dc7628158sm10007121pfg.50.2022.05.24.15.18.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 May 2022 15:18:27 -0700 (PDT) From: Stephen Hemminger To: dev@dpdk.org Cc: Stephen Hemminger , =?UTF-8?q?Mattias=20R=C3=B6nnblom?= , Ray Kinsella Subject: [RFT v2 1/3] random: add rte_rand_float() Date: Tue, 24 May 2022 15:18:22 -0700 Message-Id: <20220524221824.1037693-2-stephen@networkplumber.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220524221824.1037693-1-stephen@networkplumber.org> References: <20220524184623.480646-1-stephen@networkplumber.org> <20220524221824.1037693-1-stephen@networkplumber.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org The PIE code and other applications can benefit from having a fast way to get a random floating point value. This new function is equivalent to erand48_r in the standard library. Signed-off-by: Stephen Hemminger --- app/test/test_rand_perf.c | 7 +++++++ doc/guides/rel_notes/release_22_07.rst | 5 +++++ lib/eal/common/rte_random.c | 21 +++++++++++++++++++++ lib/eal/include/rte_random.h | 17 +++++++++++++++++ lib/eal/version.map | 1 + 5 files changed, 51 insertions(+) diff --git a/app/test/test_rand_perf.c b/app/test/test_rand_perf.c index fe797ebfa1ca..f3602da5b2d4 100644 --- a/app/test/test_rand_perf.c +++ b/app/test/test_rand_perf.c @@ -20,6 +20,7 @@ static volatile uint64_t vsum; enum rand_type { rand_type_64, + rand_type_float, rand_type_bounded_best_case, rand_type_bounded_worst_case }; @@ -30,6 +31,8 @@ rand_type_desc(enum rand_type rand_type) switch (rand_type) { case rand_type_64: return "Full 64-bit [rte_rand()]"; + case rand_type_float: + return "Floating point [rte_rand_float()]"; case rand_type_bounded_best_case: return "Bounded average best-case [rte_rand_max()]"; case rand_type_bounded_worst_case: @@ -55,6 +58,9 @@ test_rand_perf_type(enum rand_type rand_type) case rand_type_64: sum += rte_rand(); break; + case rand_type_float: + sum += rte_rand_float() * UINT64_MAX; + break; case rand_type_bounded_best_case: sum += rte_rand_max(BEST_CASE_BOUND); break; @@ -83,6 +89,7 @@ test_rand_perf(void) printf("Pseudo-random number generation latencies:\n"); test_rand_perf_type(rand_type_64); + test_rand_perf_type(rand_type_float); test_rand_perf_type(rand_type_bounded_best_case); test_rand_perf_type(rand_type_bounded_worst_case); diff --git a/doc/guides/rel_notes/release_22_07.rst b/doc/guides/rel_notes/release_22_07.rst index e49cacecefd4..128d4fca85b3 100644 --- a/doc/guides/rel_notes/release_22_07.rst +++ b/doc/guides/rel_notes/release_22_07.rst @@ -104,6 +104,11 @@ New Features * ``RTE_EVENT_QUEUE_ATTR_WEIGHT`` * ``RTE_EVENT_QUEUE_ATTR_AFFINITY`` +* ** Added function get random floating point number.** + + Added the function ``rte_rand_float()`` to provide a pseudo-random + floating point number. + Removed Items ------------- diff --git a/lib/eal/common/rte_random.c b/lib/eal/common/rte_random.c index 4535cc980cec..024c3c41dc16 100644 --- a/lib/eal/common/rte_random.c +++ b/lib/eal/common/rte_random.c @@ -6,6 +6,7 @@ #include #endif #include +#include #include #include @@ -173,6 +174,26 @@ rte_rand_max(uint64_t upper_bound) return res; } +double +rte_rand_float(void) +{ + struct rte_rand_state *state = __rte_rand_get_state(); + union ieee754_double u = { + .ieee = { + .negative = 0, + .exponent = IEEE754_DOUBLE_BIAS, + }, + }; + uint64_t val; + + /* Take 64 bit random value and put it into the mantissa */ + val = __rte_rand_lfsr258(state); + u.ieee.mantissa0 = val >> 32; /* only 20 bits used */ + u.ieee.mantissa1 = (uint32_t)val; + + return u.d - 1.0; +} + static uint64_t __rte_random_initial_seed(void) { diff --git a/lib/eal/include/rte_random.h b/lib/eal/include/rte_random.h index 29f5f1325a30..553beb2d9c6f 100644 --- a/lib/eal/include/rte_random.h +++ b/lib/eal/include/rte_random.h @@ -65,6 +65,23 @@ rte_rand(void); uint64_t rte_rand_max(uint64_t upper_bound); +/** + * @warning + * @b EXPERIMENTAL: this API may change without prior notice + * + * Generates a pseudo-random floating point number. + * + * This function returns a nonnegative double-precison floating random + * number uniformly distributed over the interval [0.0, 1.0). + * + * If called from lcore threads, this function is thread-safe. + * + * @return + * A pseudo-random value between 0 and 1.0. + */ +__rte_experimental +double rte_rand_float(void); + #ifdef __cplusplus } #endif diff --git a/lib/eal/version.map b/lib/eal/version.map index d49e30bd042f..861906af2999 100644 --- a/lib/eal/version.map +++ b/lib/eal/version.map @@ -422,6 +422,7 @@ EXPERIMENTAL { rte_intr_type_set; # added in 22.07 + rte_rand_float; rte_thread_get_affinity_by_id; rte_thread_self; rte_thread_set_affinity_by_id; -- 2.35.1