7 Commits

Author SHA1 Message Date
Paul E. McKenney
3b6e1dd423 rcutorture: Allow rcutorture without RCU Tasks
Currently, a CONFIG_PREEMPT_NONE=y kernel substitutes normal RCU for
RCU Tasks.  Unless that kernel builds rcutorture, whether built-in or as
a module, in which case RCU Tasks is (unnecessarily) used.  This both
increases kernel size and increases the complexity of certain tracing
operations.  This commit therefore decouples the presence of rcutorture
from the presence of RCU Tasks.

However, there is a need to select CONFIG_TASKS_RCU for testing purposes.
Except that casual users must not be bothered with questions -- for them,
this needs to be fully automated.  There is thus a CONFIG_FORCE_TASKS_RCU
that selects CONFIG_TASKS_RCU, is user-selectable, but which depends
on CONFIG_RCU_EXPERT.

[ paulmck: Apply kernel test robot feedback. ]

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20 16:53:19 -07:00
Paul E. McKenney
de2909461c rcutorture: Upgrade two-CPU scenarios to four CPUs
There is no way to place the vCPUs in a two-CPU rcutorture scenario to
get variable memory latency.  This commit therefore upgrades the current
two-CPU rcutorture scenarios to four CPUs.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-07-27 11:41:32 -07:00
Paul E. McKenney
9f8ba55d49 rcutorture: Remove CONFIG_HOTPLUG_CPU=n from scenarios
A number of mainstream CPU families are no longer capable of building
kernels having CONFIG_SMP=y and CONFIG_HOTPLUG_CPU=n, so this commit
removes this combination from the rcutorture scenarios having it.
People wishing to try out this combination may still do so using the
"--kconfig CONFIG_HOTPLUG_CPU=n CONFIG_SUSPEND=n CONFIG_HIBERNATION=n"
argument to the tools/testing/selftests/rcutorture/bin/kvm.sh script
that is used to run rcutorture.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-10-05 11:49:13 -07:00
Paul E. McKenney
a7c8655b07 sched/isolation: Eliminate NO_HZ_FULL_ALL
Commit 6f1982fedd59 ("sched/isolation: Handle the nohz_full= parameter")
broke CONFIG_NO_HZ_FULL_ALL=y kernels.  This breakage is due to the code
under CONFIG_NO_HZ_FULL_ALL failing to invoke the shiny new housekeeping
functions.  This means that rcutorture scenario TREE04 now emits RCU CPU
stall warnings due to the RCU grace-period kthreads not being awakened
at a time of their choosing, or perhaps even not at all:

[   27.731422] rcu_bh kthread starved for 21001 jiffies! g18446744073709551369 c18446744073709551368 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x402 ->cpu=3
[   27.731423] rcu_bh          I14936     9      2 0x80080000
[   27.731435] Call Trace:
[   27.731440]  __schedule+0x31a/0x6d0
[   27.731442]  schedule+0x31/0x80
[   27.731446]  schedule_timeout+0x15a/0x320
[   27.731453]  ? call_timer_fn+0x130/0x130
[   27.731457]  rcu_gp_kthread+0x66c/0xea0
[   27.731458]  ? rcu_gp_kthread+0x66c/0xea0

Because no one has complained about CONFIG_NO_HZ_FULL_ALL=y being broken,
I hypothesize that no one is in fact using it, other than rcutorture.
This commit therefore eliminates CONFIG_NO_HZ_FULL_ALL and updates
rcutorture's config files to instead use the nohz_full= kernel parameter
to put the desired CPUs into nohz_full mode.

Fixes: 6f1982fedd59 ("sched/isolation: Handle the nohz_full= parameter")

Reported-by: kernel test robot <xiaolong.ye@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Jonathan Corbet <corbet@lwn.net>
2018-02-15 15:40:37 -08:00
Paul E. McKenney
c4295bfe7e rcutorture: Make rcutorture scripts force RCU_EXPERT
This commit causes the rcutorture scripts to force RCU_EXPERT so that
these scripts can cause rcutorture to torture RCU in the various required
configurations.  However, SRCU-P, TASKS03, and TREE09 retain !RCU_EXPERT
in order to ensure testing of the vanilla configuration.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2015-05-27 12:59:59 -07:00
Paul E. McKenney
9a8e7062f6 rcutorture: TASKS_RCU set directly, so don't explicitly set it
The TASKS01, TASKS02, and TASKS03 rcutorture config fragments currently
set CONFIG_TASKS_RCU.  However, now that the value of this Kconfig
parameter is set via "select" statements, it is no longer necessary to
set it explicitly.  This commit therefore removes it from the Kconfig
fragments.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2015-05-27 12:59:59 -07:00
Paul E. McKenney
f1a828f5fa rcutorture: Add RCU-tasks test cases
This commit adds the TASKS01 and TASKS02 Kconfig fragments, along with
the corresponding TASKS01.boot and TASKS02.boot boot-parameter files
specifying that rcutorture test RCU-tasks instead of the default flavor.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:27:25 -07:00