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* rcutorture: Fix error return code in rcu_perf_init()Wei Yongjun2016-06-141-1/+3
| | | | | | | | Fix to return a negative error code -ENOMEM from kcalloc() error handling case instead of 0, as done elsewhere in this function. Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcuperf: Don't treat gp_exp mis-setting as a WARNBoqun Feng2016-06-141-3/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | 0day found a boot warning triggered in rcu_perf_writer() on !SMP kernel: WARN_ON(rcu_gp_is_normal() && gp_exp); , the root cause of which is trying to measure expedited grace periods(by setting gp_exp to true by default) when all the grace periods are normal(TINY RCU only has normal grace periods). However, such a mis-setting would only result in failing to measure the performance for a specific kind of grace periods, therefore using a WARN_ON to check this is a little overkilling. We could handle this inside rcuperf module via some error messages to tell users about the mis-settings. Therefore this patch removes the WARN_ON in rcu_perf_writer() and handles those checkings in rcu_perf_init() with plain if() code. Moreover, this patch changes the default value of gp_exp to 1) align with rcutorture tests and 2) make the default setting work for all RCU implementations by default. Suggested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Fixes: http://lkml.kernel.org/r/57411b10.mFvG0+AgcrMXGtcj%fengguang.wu@intel.com Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* torture: Simplify code, eliminate RCU_PERF_TEST_RUNNABLEPaul E. McKenney2016-06-141-6/+1
| | | | | | | | This commit applies the infamous IS_ENABLED() macro to eliminate a #ifdef. It also eliminates the RCU_PERF_TEST_RUNNABLE Kconfig option in favor of the already-existing rcuperf.perf_runnable kernel boot parameter. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcuperf: Do not wake up shutdown wait queue if "shutdown" is false.Artem Savkov2016-03-311-2/+4
| | | | | | | | | | | After finishing its tests rcuperf tries to wake up shutdown_wq even if "shutdown" param is set to false, resulting in a wake_up() call on an unitialized wait_queue_head_t which leads to "BUG: spinlock bad magic" and "BUG: unable to handle kernel NULL pointer dereference". Fix by checking "shutdown" param before waking up the queue. Signed-off-by: Artem Savkov <artem.savkov@gmail.com>
* rcutorture: Avoid RCU CPU stall warning and RT throttlingPaul E. McKenney2016-03-311-0/+4
| | | | | | | | | | | | | | Running rcuperf can result in RCU CPU stall warnings and RT throttling. These occur because on of the real-time writer processes does ftrace_dump() while still running at real-time priority. This commit therefore prevents these problems by setting the writer thread back to SCHED_NORMAL (AKA SCHED_OTHER) before doing ftrace_dump(). In addition, this commit adds a small fixed delay before dumping ftrace buffer in order to decrease the probability that this dumping will interfere with other writers' grace periods. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcutorture: Add rcuperf holdoff boot parameter to reduce interferencePaul E. McKenney2016-03-311-0/+5
| | | | | | | | Boot-time activity can legitimately grab CPUs for extended time periods, so the commit adds a boot parameter to delay the start of the performance test until boot has completed. Defaults to 10 seconds. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcutorture: Make rcuperf collect expedited event-trace dataPaul E. McKenney2016-03-311-0/+1
| | | | | | | | | This commit enables ftrace in the rcuperf TREE kernel build and adds an ftrace_dump() at the end of rcuperf processing. This data will be used to measure the actual durations of the expedited grace periods without the added delays inherent in the kernel-module measurements. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcutorture: Set rcuperf writer kthreads to real-time priorityPaul E. McKenney2016-03-311-0/+3
| | | | | | | This commit forces more deterministic update-side behavior by setting rcuperf's rcu_perf_writer() kthreads to real-time priority. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcutorture: Bind rcuperf reader/writer kthreads to CPUsPaul E. McKenney2016-03-311-1/+4
| | | | | | | | This commit forces more deterministic behavior by binding rcuperf's rcu_perf_reader() and rcu_perf_writer() kthreads to their respective CPUs. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcutorture: Add RCU grace-period performance testsPaul E. McKenney2016-03-311-0/+637
This commit adds a new rcuperf module that carries out simple performance tests of RCU grace periods. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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