From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 3EE94A0550; Wed, 25 May 2022 13:55:22 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id D2FC740146; Wed, 25 May 2022 13:55:21 +0200 (CEST) Received: from mail-108-mta248.mxroute.com (mail-108-mta248.mxroute.com [136.175.108.248]) by mails.dpdk.org (Postfix) with ESMTP id E2C34400EF for ; Wed, 25 May 2022 13:55:19 +0200 (CEST) Received: from filter006.mxroute.com ([140.82.40.27] 140.82.40.27.vultrusercontent.com) (Authenticated sender: mN4UYu2MZsgR) by mail-108-mta248.mxroute.com (ZoneMTA) with ESMTPSA id 180fb122e56000c327.001 for (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES128-GCM-SHA256); Wed, 25 May 2022 11:55:14 +0000 X-Zone-Loop: ff3dba2c22176ebe98ae0bdbe3719b445ae285b95f9e X-Originating-IP: [140.82.40.27] DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=ashroe.eu; s=x; h=Content-Type:MIME-Version:Message-ID:Date:In-reply-to:Subject:Cc:To: From:References:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=U+KfYdEzC32Cz1IWgZ1+hURIbjmOwCJx3NAKY2J6yE8=; b=MUDYzf34U2MI359QAvsxQAslC9 tXkmU0LKCXOGFyERMdOUnWrLfZEPqd4gWqpMOARnNC372S75EDWXnnd8p/bzkayJhZntDgRVZFITj zSUbE/SlQxl5Id2xziJ8b87GNhVvKYs4hFqD27do3LhwDpnzuT/HGM+S1/sDG3QeqPlRsseTLjLwI Y9x4WVLOaotQVN5goD64z66Tk9z0MrkOcbUdIurLjSWcxeWdw6etUMx/MkwRJZO2XhZ5CaHgzZIcp vXTFRa+hLldcXZjtePFihtdxn70gsfz90n1z4FyJTUaOl/lVCWg0bTHuNRXmxzCSEhrITWV9/VzMl AhNFiu3w==; References: <20220524184623.480646-1-stephen@networkplumber.org> <20220524221824.1037693-1-stephen@networkplumber.org> <20220524221824.1037693-2-stephen@networkplumber.org> User-agent: mu4e 1.4.15; emacs 27.1 From: Ray Kinsella To: Stephen Hemminger Cc: dev@dpdk.org, Mattias =?utf-8?Q?R=C3=B6nnblom?= Subject: Re: [RFT v2 1/3] random: add rte_rand_float() In-reply-to: <20220524221824.1037693-2-stephen@networkplumber.org> Date: Wed, 25 May 2022 12:55:11 +0100 Message-ID: <87bkvlzv1c.fsf@mdr78.vserver.site> MIME-Version: 1.0 Content-Type: text/plain X-AuthUser: mdr@ashroe.eu 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 Stephen Hemminger writes: > 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; Niggle - is there an alignment issue on the line above? > rte_thread_get_affinity_by_id; > rte_thread_self; > rte_thread_set_affinity_by_id; -- Regards, Ray K