On 4/21/2025 1:47 PM, Joel Fernandes wrote:
> Currently, the ->gpwrap is not tested (at all per my testing) due to the
> requirement of a large delta between a CPU's rdp->gp_seq and its node's
> rnp->gpseq.
>
> This results in no testing of ->gpwrap being set. This patch by default
> adds 5 minutes of testing with ->gpwrap forced by lowering the delta
> between rdp->gp_seq and rnp->gp_seq to just 8 GPs. All of this is
> configurable, including the active time for the setting and a full
> testing cycle.
>
> By default, the first 25 minutes of a test will have the _default_
> behavior there is right now (ULONG_MAX / 4) delta. Then for 5 minutes,
> we switch to a smaller delta causing 1-2 wraps in 5 minutes. I believe
> this is reasonable since we at least add a little bit of testing for
> usecases where ->gpwrap is set.
>
> Tested-by: Paul E. McKenney <paul...@kernel.org>
> Signed-off-by: Joel Fernandes <joelagn...@nvidia.com>
> ---
> v4->v5
> - Added gpwrap_lag torture param to turn off entire test.
> - replaced references to 'ovf' with 'gpwrap lag'.
>
> Will move this to my rcu/torture-for-6.16 and update my rcu/for-next branches.
>
> .../admin-guide/kernel-parameters.txt | 5 ++
> kernel/rcu/rcu.h | 4 ++
> kernel/rcu/rcutorture.c | 72 ++++++++++++++++++-
> kernel/rcu/tree.c | 34 ++++++++-
> kernel/rcu/tree.h | 1 +
> 5 files changed, 113 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt
> b/Documentation/admin-guide/kernel-parameters.txt
> index 76e538c77e31..e1d11b6595fd 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -5657,6 +5657,11 @@
> are zero, rcutorture acts as if is interpreted
> they are all non-zero.
>
> + rcutorture.gpwrap_lag= [KNL]
> + Enable grace-period wrap lag testing. Setting
> + to false prevents the gpwrap lag test from
> + running.
> +
FYI, I added docs for the additional params here as well:
+ rcutorture.gpwrap_lag= [KNL]
+ Enable grace-period wrap lag testing. Setting
+ to false prevents the gpwrap lag test from
+ running.
+
+ rcutorture.gpwrap_lag_gps= [KNL]
+ Set the value for grace-period wrap lag during
+ active lag testing periods. This controls how many
+ grace periods differences we tolerate between
+ rdp and rnp's gp_seq before setting overflow flag.
+
+ rcutorture.gpwrap_lag_cycle_mins= [KNL]
+ Set the total cycle duration for gpwrap lag
+ testing in minutes. This is the total time for
+ one complete cycle of active and inactive
+ testing periods. Default is 30 minutes.
+
+ rcutorture.gpwrap_lag_active_mins= [KNL]
+ Set the duration for which gpwrap lag is active
+ within each cycle, in minutes. During this time,
+ the grace-period wrap lag will be set to the
+ value specified by gpwrap_lag_gps. Default is
+ 5 minutes.
+
Will push this to my rcu/torture-for-6.16 and also update my rcu/for-next
branch.
- Joel
