linux-toradex.git/kernel/rcu/rcuperf.c, branch v4.9.97

rcuperf: Consistently insert space between flag and message

2016-08-22T17:06:16+00:00

A few rcuperf dmesg output messages have no space between the flag and
the start of the message. In contrast, every other messages consistently
supplies a single space.  This difference makes rcuperf dmesg output
hard to read and to mechanically parse.  This commit therefore fixes
this problem by modifying a pr_alert() call and PERFOUT_STRING() macro
function to provide that single space.

Signed-off-by: SeongJae Park 
Signed-off-by: Paul E. McKenney

rcutorture: Fix error return code in rcu_perf_init()

2016-06-14T23:03:32+00:00

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

2016-06-14T23:03:31+00:00

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

2016-06-14T23:02:15+00:00

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.

2016-03-31T20:39:51+00:00

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

2016-03-31T20:39:47+00:00

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

2016-03-31T20:38:58+00:00

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

2016-03-31T20:38:53+00:00

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

2016-03-31T20:37:39+00:00

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

2016-03-31T20:37:39+00:00

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