The jitter.sh script has some entertaining awk code to generate a
hex mask from a randomly selected CPU number, which is handed to the
"taskset" command. Except that this command has a "-c" parameter to
take a comma/dash-separated list of CPU numbers. This commit therefore
saves a few lines of awk by switching to a single-number CPU list.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Remote rcutorture testing requires that jitter.sh continue to be
invoked from the generated script for local runs, but that it instead
be invoked on the remote system for distributed runs. This argues
for common jitterstart and jitterstop scripts. But it would be good
for jitterstart and jitterstop to control the name and location of the
"jittering" file, while continuing to have the duration controlled by
the caller of these new scripts.
This commit therefore reverses the order of the jittering and duration
parameters for jitter.sh, so that the jittering parameter precedes the
duration parameter.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently, jitter.sh execution is controlled by a time limit and by the
"kill" command. The former allowed jitter.sh to run uselessly past
the end of a set of runs that panicked during boot, and the latter is
vulnerable to PID reuse. This commit therefore introduces a "jittering"
file in the date-stamp directory within "res" that must be present for
the jitter.sh scripts to continue executing. The time limit is still
in place in order to avoid disturbing runs featuring large trace dumps,
but the removal of the "jittering" file handles the panic-during-boot
scenario without relying on PIDs.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The current jitter.sh script expects cpumask bits to fit into whatever
the awk interpreter uses for an integer, which clearly does not hold for
even medium-sized systems these days. This means that on a large system,
only the first 32 or 64 CPUs (depending) are subjected to jitter.sh
CPU-time perturbations. This commit therefore computes a given CPU's
cpumask using text manipulation rather than arithmetic shifts.
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
When bisecting RCU issues, it is often the case that the first error in
an unsuccessful run will happen quickly, but that a successful run must
go on for some time in order to obtain a sufficiently low false-negative
error rate. In many cases, a bisection requires multiple concurrent
runs, in which case the first failure in any run indicates failure,
pure and simple. In such cases, it would speed things up greatly if
the first failure terminated all runs.
This commit therefore adds scripting that checks for a file named "STOP"
in the top-level results directory, terminating the run when it appears.
Note that in-progress builds will continue until completion, but future
builds and all runs will be cut short.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently, jitter.sh assumes that the underlying hypervisor will be
configured with all CPUs hotpluggable, with the possible exception
of CPU 0. However, there are installations where the hypervisor
prohibits offlining, which breaks jitter.sh. This commit therefore
lists the CPUs that cannot be offlined up front, and checks for the
case where no CPU can be offlined in the loop.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
In many environments, gawk provides systime(), but awk doesn't.
This commit therefore changes awk scripts using systime() to instead be
gawk scripts.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
jitter.sh currently does not add CPU0 to the list of CPUs for adding of
jitter. Let us add it to this list even when it is not hot-pluggable.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
The rcutorture jitter.sh script selects a random CPU but does not check
if it is offline or online. This leads to taskset errors many times. On
my machine, hyper threading is disabled so half the cores are offline
causing taskset errors a lot of times. Let us fix this by checking from
only the online CPUs on the system.
Cc: rcu@vger.kernel.org
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address and add copyright notices.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
This commit adds a --jitter OS-jitter capability to expose bugs based
on no-delay assumptions.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
