The TREE01.boot nr_cpus kernel boot parameter has been set to 43 for
more than seven years, but it can cause RCU CPU stall warnings on arm64,
most of the time involving the stop-machine subsystem. This should
not be too surprising, given that this causes 43 vCPUs to spin with
interrupts disabled when there are only eight physical CPUs.
The point of this CPU overcommit is to test the ability of expedited RCU
grace period initialization to handle races with incoming CPUs that have
never previously been online. But limiting to 17 CPUs instead of 43
allows time for this code to be exercised, and eliminates (or at least
greatly reduces) the incidence of RCU CPU stall warnings on arm64.
So this commit therefore sets nr_cpus=17 in TREE01.boot.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
This commit adds periodic toggling of 7 of 8 CPUs every second to TREE01
in order to test NOCB toggle code.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Because TREE01 can end up running more vCPUs that physical CPUs,
hammering these shortchanged CPUs with tight loops containing call_rcu()
invocations seems a bit like overkill. This commit therefore exempts
TREE01 from rcutorture's forward-progress testing.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Now that the RCU-bh and RCU-sched update-side functions are simple
wrappers around their RCU counterparts, there isn't a whole lot of
point in testing them. This commit therefore removes the self-test
capability and removes the corresponding kernel-boot parameters.
It also updates the various rcutorture .boot files to remove the
kernel boot parameters that call for testing RCU-bh and RCU-sched.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The maxcpus= kernel boot parameter limits the number of CPUs brought
online at boot time, but it does nothing to prevent additional CPUs
from being brought up later. Placing a hard cap on the total number
of CPUs is instead the job of the nr_cpus= boot parameter. This commit
therefore switches the configfrag_boot_cpus() shell function from maxcpus=
to nr_cpus=. This commit also adds a nr_cpus=43 kernel parameter to RCU's
TREE01 test scenario, but retains the maxcpus=8 kernel parameter in order
to test the ability of RCU expedited grace periods to handle new CPUs
coming online for the first time during grace-period initialization.
Finally, this commit makes the torture scheduling allow maxcpus= to
override other means of specifying the number of CPUs to allow for.
This last works because the torture kernel modules size their workloads
based on the number of CPUs present at the start of the test, not the
ultimate number of CPUs.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The CONFIG_RCU_NOCB_CPU_ALL, CONFIG_RCU_NOCB_CPU_NONE, and
CONFIG_RCU_NOCB_CPU_ZERO Kconfig options are used only in testing and
are redundant with the rcu_nocbs= boot parameter. This commit therefore
removes these three Kconfig options and adjusts the rcutorture scripts
to use the boot parameter instead.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The RCU_TORTURE_TEST_SLOW_PREINIT, RCU_TORTURE_TEST_SLOW_PREINIT_DELAY,
RCU_TORTURE_TEST_SLOW_PREINIT_DELAY, RCU_TORTURE_TEST_SLOW_INIT,
RCU_TORTURE_TEST_SLOW_INIT_DELAY, RCU_TORTURE_TEST_SLOW_CLEANUP,
and RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY Kconfig options are only
useful for torture testing, and there are the rcutree.gp_cleanup_delay,
rcutree.gp_init_delay, and rcutree.gp_preinit_delay kernel boot parameters
that rcutorture can use instead. The effect of these parameters is to
artificially slow down grace period initialization and cleanup in order
to make some types of race conditions happen more often.
This commit therefore simplifies Tree RCU a bit by removing the Kconfig
options and adding the corresponding kernel parameters to rcutorture's
.boot files instead. However, this commit also leaves out the kernel
parameters for TREE02, TREE04, and TREE07 in order to have about the
same number of tests slowed as not slowed. TREE01, TREE03, TREE05,
and TREE06 are slowed, and the rest are not slowed.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Setting CONFIG_MAXSMP=y causes cpumasks to be moved offstack, which
introduces the possibility of NULL cpumask_var_t pointers. This commit
therefore enables CONFIG_MAXSMP=y in TREE01 to increase test coverage.
However, because CONFIG_MAXSMP=y implies 8192 CPUs, we need to use
the maxcpus= boot parameter to limit the number of CPUs to something
reasonable, which in turn requires updating the scripts to handle this.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
This commit uses the standard software ploy of introducing another
level of indirection below the configs directory. This allows each
torture-test suite to have its own set of Kconfig files, boot parameters,
and version-specific scripts. Initially, we have only rcu, but lock
will follow soonish.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
