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[34.150.221.228]) by smtp.gmail.com with ESMTPSA id h3-20020a05620a400300b006fc447eebe5sm8562757qko.27.2022.12.13.12.48.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Dec 2022 12:48:43 -0800 (PST) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org Cc: "Joel Fernandes (Google)" , Davidlohr Bueso , Josh Triplett , "Paul E. McKenney" , rcu@vger.kernel.org, connoro@google.com Subject: [PATCH v3 rcu/dev 2/2] locktorture: Make the rt_boost factor a tunable Date: Tue, 13 Dec 2022 20:48:39 +0000 Message-Id: <20221213204839.321027-2-joel@joelfernandes.org> X-Mailer: git-send-email 2.39.0.314.g84b9a713c41-goog In-Reply-To: <20221213204839.321027-1-joel@joelfernandes.org> References: <20221213204839.321027-1-joel@joelfernandes.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org The rt boosting in locktorture has a factor variable s currently large enough that boosting only happens once every minute or so. Add a tunable to reduce the factor so that boosting happens more often, to test paths and arrive at failure modes earlier. With this change, I can set the factor to like 50 and have the boosting happens every 10 seconds or so. Tested with boot parameters: locktorture.torture_type=mutex_lock locktorture.onoff_interval=1 locktorture.nwriters_stress=8 locktorture.stutter=0 locktorture.rt_boost=1 locktorture.rt_boost_factor=50 locktorture.nlocks=3 [ Apply Davidlohr Bueso feedback on quoting rt_boost_factor. ] Signed-off-by: Joel Fernandes (Google) --- kernel/locking/locktorture.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c index e2271e8fc302..87e861da0ad5 100644 --- a/kernel/locking/locktorture.c +++ b/kernel/locking/locktorture.c @@ -48,6 +48,7 @@ torture_param(int, stat_interval, 60, torture_param(int, stutter, 5, "Number of jiffies to run/halt test, 0=disable"); torture_param(int, rt_boost, 2, "Do periodic rt-boost. 0=Disable, 1=Only for rt_mutex, 2=For all lock types."); +torture_param(int, rt_boost_factor, 50, "A factor determining how often rt-boost happens."); torture_param(int, verbose, 1, "Enable verbose debugging printk()s"); @@ -131,12 +132,12 @@ static void torture_lock_busted_write_unlock(int tid __maybe_unused) static void __torture_rt_boost(struct torture_random_state *trsp) { - const unsigned int factor = 50000; /* yes, quite arbitrary */ + const unsigned int factor = rt_boost_factor; if (!rt_task(current)) { /* - * Boost priority once every ~50k operations. When the - * task tries to take the lock, the rtmutex it will account + * Boost priority once every 'rt_boost_factor' operations. When + * the task tries to take the lock, the rtmutex it will account * for the new priority, and do any corresponding pi-dance. */ if (trsp && !(torture_random(trsp) % @@ -146,8 +147,9 @@ static void __torture_rt_boost(struct torture_random_state *trsp) return; } else { /* - * The task will remain boosted for another ~500k operations, - * then restored back to its original prio, and so forth. + * The task will remain boosted for another 10 * 'rt_boost_factor' + * operations, then restored back to its original prio, and so + * forth. * * When @trsp is nil, we want to force-reset the task for * stopping the kthread.