kernel.git/kernel/rcu/rcuperf.c, branch linux-4.8.y

rcutorture: Fix error return code in rcu_perf_init()

2016-06-14T23:03:32Z

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 Signed-off-by: Paul E. McKenney

rcuperf: Don't treat gp_exp mis-setting as a WARN

2016-06-14T23:03:31Z

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 Signed-off-by: Boqun Feng Fixes: http://lkml.kernel.org/r/57411b10.mFvG0+AgcrMXGtcj%fengguang.wu@intel.com Signed-off-by: Paul E. McKenney

torture: Simplify code, eliminate RCU_PERF_TEST_RUNNABLE

2016-06-14T23:02:15Z

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

rcuperf: Do not wake up shutdown wait queue if "shutdown" is false.

2016-03-31T20:39:51Z

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

rcutorture: Avoid RCU CPU stall warning and RT throttling

2016-03-31T20:39:47Z

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

rcutorture: Add rcuperf holdoff boot parameter to reduce interference

2016-03-31T20:38:58Z

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

rcutorture: Make rcuperf collect expedited event-trace data

2016-03-31T20:38:53Z

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

rcutorture: Set rcuperf writer kthreads to real-time priority

2016-03-31T20:37:39Z

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

rcutorture: Bind rcuperf reader/writer kthreads to CPUs

2016-03-31T20:37:39Z

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

rcutorture: Add RCU grace-period performance tests

2016-03-31T20:37:38Z

This commit adds a new rcuperf module that carries out simple performance tests of RCU grace periods. Signed-off-by: Paul E. McKenney