kernel.git/kernel/rcu/rcuperf.c, branch linux-4.13.y

rcu: Move expediting-related access/control out of rcupdate.h

2017-06-09T01:52:28Z

The rcu_gp_is_normal(), rcu_gp_is_expedited(), rcu_expedite_gp(), and rcu_unexpedite_gp() functions are intended only for use within the RCU implementation itself -- the sysfs access is what should be used outside of RCU. This commit therefore moves the declarations for these functions to kernel/rcu/rcu.h, and also includes this file into kernel/rcu/rcutorture.c and kernel/rcu/rcuperf.c. This also has the beneficial effect of shrinking rcupdate.c a bit. Reported-by: Ingo Molnar Signed-off-by: Paul E. McKenney

rcuperf: Add writer_holdoff boot parameter

2017-06-08T15:25:32Z

This commit adds a writer_holdoff boot parameter to rcuperf, which is intended to be used to test Tree SRCU's auto-expediting. This boot parameter is in microseconds, and defaults to zero (that is, disabled). Set it to a bit larger than srcutree.exp_holdoff, keeping the nanosecond/microsecond conversion, to force Tree SRCU to auto-expedite more aggressively. This commit also adds documentation for this parameter, and fixes some alphabetization while in the neighborhood. Signed-off-by: Paul E. McKenney

rcuperf: Set more user-friendly defaults

2017-06-08T15:25:31Z

Common-case use of rcuperf must set rcuperf.nreaders=0 and if not built as a module, rcuperf.shutdown. This commit therefore sets the default for rcuperf.nreaders to zero and sets the default for rcuperf.shutdown to zero if rcuperf is built as a module and to one otherwise. Signed-off-by: Paul E. McKenney

rcuperf: Add test for dynamically initialized srcu_struct

2017-06-08T15:25:28Z

This commit adds a perf_type of "srcud", which species that rcuperf test SRCU on a dynamically initialized srcu_struct. Signed-off-by: Paul E. McKenney

rcuperf: Add ability to performance-test call_rcu() and friends

2017-06-08T15:25:26Z

This commit upgrades rcuperf so that it can do performance testing on asynchronous grace-period primitives such as call_srcu(). There is a new rcuperf.gp_async module parameter that specifies this new behavior, with the pre-existing rcuperf.gp_exp testing expedited grace periods such as synchronize_rcu_expedited, and with the default being to test synchronous non-expedited grace periods such as synchronize_rcu(). There is also a new rcuperf.gp_async_max module parameter that specifies the maximum number of outstanding callbacks per writer kthread, defaulting to 1,000. When this limit is exceeded, the writer thread invokes the appropriate flavor of rcu_barrier() to wait for callbacks to drain. Signed-off-by: Paul E. McKenney [ paulmck: Removed the redundant initialization noted by Arnd Bergmann. ]

rcuperf: Defer expedited/normal check to end of test

2017-06-08T15:25:24Z

Current rcuperf startup checks to see if the user asked to measure only expedited grace periods, yet constrained all grace periods to be normal, or if the user asked to measure only normal grace periods, yet constrained all grace periods to be expedited. Useless tests of this sort are aborted. Unfortunately, making RCU work through the mid-boot dead zone [1] puts RCU into expedited-only mode during that zone. Which happens to also be the exact time that rcuperf carries out the aforementioned check. So if the user asks rcuperf to measure only normal grace periods (the default), rcuperf will now always complain and terminate the test. This commit therefore moves the checks to rcu_perf_cleanup(). This has the disadvantage of failing to abort useless tests, but avoids the need to create yet another kthread and the need to do fiddly checks involving the holdoff time. (Yes, another approach is to do the checks in a late-stage init function, but that would require some way to communicate badness to rcuperf's kthreads, and seems not worth the bother.) [1] https://lwn.net/Articles/716148/ Signed-off-by: Paul E. McKenney

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:27Z

We are going to move scheduler ABI details to , which will be used from a number of .c files. Create empty placeholder header that maps to . Include the new header in the files that are going to need it. Acked-by: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

rcuperf: Consistently insert space between flag and message

2016-08-22T17:06:16Z

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()

2016-06-14T23:03:32Z

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