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[204.195.96.226]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2dd3f0faed5sm46132145ad.10.2026.09.14.09.47.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Sep 2026 09:47:07 -0700 (PDT) Date: Mon, 14 Sep 2026 09:46:56 -0700 From: Stephen Hemminger To: Mattias =?UTF-8?B?UsO2bm5ibG9t?= Cc: dev@dpdk.org, Morten =?UTF-8?B?QnLDuHJ1cA==?= , Mattias =?UTF-8?B?UsO2bm5ibG9t?= Subject: Re: [PATCH v2] eal: allow setting random number generator seed Message-ID: <20260914094656.3c9161e7@phoenix.local> In-Reply-To: References: <20260911225845.3168061-1-stephen@networkplumber.org> <20260912161744.201627-1-stephen@networkplumber.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable 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 On Mon, 14 Sep 2026 13:29:22 +0200 Mattias R=C3=B6nnblom wrote: > Den 2026-09-12 kl. 18:16, skrev Stephen Hemminger: > > Many performance tests use rte_rand() and the random number > > can perturb the results. Add an ability to override the automatic > > random seed on DPDK startup. =20 >=20 > There is a way to seed the PRNG already, rte_srand(). Why the tests=20 > can't use this? >=20 > Provided the test results depend on something that use the PRNG before=20 > the test driver has had the opportunity to call rte_srand(), controlling= =20 > the *initial* seed may be required. >=20 > I don't think this feature should be controlled by an environment=20 > variable. There is no precedent for that. If this functionality is=20 > deemed useful, it should be an EAL command line option, it seems to me. There are several tests already using rte_srand() so that is one option. The choice of environment variable was to match the existing test harness infrastructure that uses MALLOC_PERTURB to pre-seed malloc.