| Message ID | 20230203064054.3418539-1-qiang1.zhang@intel.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 38c1e8adc5c51fdd2acb9c4362765e78fed2979b |
| Headers | show |
| Series | [v4] rcutorture: Create nocb tasks only for rcu testing and CONFIG_RCU_NOCB_CPU=y kernel | expand |
On Fri, Feb 3, 2023 at 1:35 AM Zqiang <qiang1.zhang@intel.com> wrote: > > When setting nocbs_nthreads to start rcutorture test with a non-zero value, > the nocb tasks will be created and invoke rcu_nocb_cpu_offload/deoffload() > to toggle CPU's callback-offload state, but this is meaningless for non-rcu > testing or CONFIG_RCU_NOCB_CPU=n kernel create nocb tasks to periodically > toggle CPU's callback-offload state and adds unnecessary testing overhead. > > This commit therefore add checks for cur_ops types and CONFIG_RCU_NOCB_CPU > options when nocbs_nthreads is non-zero to avoid unnecessary nocb task > creation. > > Signed-off-by: Zqiang <qiang1.zhang@intel.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> thanks, - Joel > --- > kernel/rcu/rcutorture.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c > index 297da28ce92d..d01127e0e8cd 100644 > --- a/kernel/rcu/rcutorture.c > +++ b/kernel/rcu/rcutorture.c > @@ -3708,6 +3708,12 @@ rcu_torture_init(void) > pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n"); > fqs_duration = 0; > } > + if (nocbs_nthreads != 0 && (cur_ops != &rcu_ops || > + !IS_ENABLED(CONFIG_RCU_NOCB_CPU))) { > + pr_alert("rcu-torture types: %s and CONFIG_RCU_NOCB_CPU=%d, nocb toggle disabled.\n", > + cur_ops->name, IS_ENABLED(CONFIG_RCU_NOCB_CPU)); > + nocbs_nthreads = 0; > + } > if (cur_ops->init) > cur_ops->init(); > > -- > 2.25.1 >
On Fri, Feb 03, 2023 at 12:29:23PM -0500, Joel Fernandes wrote: > On Fri, Feb 3, 2023 at 1:35 AM Zqiang <qiang1.zhang@intel.com> wrote: > > > > When setting nocbs_nthreads to start rcutorture test with a non-zero value, > > the nocb tasks will be created and invoke rcu_nocb_cpu_offload/deoffload() > > to toggle CPU's callback-offload state, but this is meaningless for non-rcu > > testing or CONFIG_RCU_NOCB_CPU=n kernel create nocb tasks to periodically > > toggle CPU's callback-offload state and adds unnecessary testing overhead. > > > > This commit therefore add checks for cur_ops types and CONFIG_RCU_NOCB_CPU > > options when nocbs_nthreads is non-zero to avoid unnecessary nocb task > > creation. > > > > Signed-off-by: Zqiang <qiang1.zhang@intel.com> > > Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Queued and pushed, thank you both! Note that this loses testing of the offload/de-offload API when there is nothing to offload or de-offload, but that is not necessarily the job of rcutorture. Or if it is the job of rcutorture, perhaps it is a single pair of calls somewhere. And that can certainly be a separate patch. But perhaps Frederic has an opinion on what testing is needed for this case, and if so where that testing should live. Thanx, Paul > thanks, > > - Joel > > > > --- > > kernel/rcu/rcutorture.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c > > index 297da28ce92d..d01127e0e8cd 100644 > > --- a/kernel/rcu/rcutorture.c > > +++ b/kernel/rcu/rcutorture.c > > @@ -3708,6 +3708,12 @@ rcu_torture_init(void) > > pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n"); > > fqs_duration = 0; > > } > > + if (nocbs_nthreads != 0 && (cur_ops != &rcu_ops || > > + !IS_ENABLED(CONFIG_RCU_NOCB_CPU))) { > > + pr_alert("rcu-torture types: %s and CONFIG_RCU_NOCB_CPU=%d, nocb toggle disabled.\n", > > + cur_ops->name, IS_ENABLED(CONFIG_RCU_NOCB_CPU)); > > + nocbs_nthreads = 0; > > + } > > if (cur_ops->init) > > cur_ops->init(); > > > > -- > > 2.25.1 > >
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 297da28ce92d..d01127e0e8cd 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -3708,6 +3708,12 @@ rcu_torture_init(void) pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n"); fqs_duration = 0; } + if (nocbs_nthreads != 0 && (cur_ops != &rcu_ops || + !IS_ENABLED(CONFIG_RCU_NOCB_CPU))) { + pr_alert("rcu-torture types: %s and CONFIG_RCU_NOCB_CPU=%d, nocb toggle disabled.\n", + cur_ops->name, IS_ENABLED(CONFIG_RCU_NOCB_CPU)); + nocbs_nthreads = 0; + } if (cur_ops->init) cur_ops->init();
When setting nocbs_nthreads to start rcutorture test with a non-zero value, the nocb tasks will be created and invoke rcu_nocb_cpu_offload/deoffload() to toggle CPU's callback-offload state, but this is meaningless for non-rcu testing or CONFIG_RCU_NOCB_CPU=n kernel create nocb tasks to periodically toggle CPU's callback-offload state and adds unnecessary testing overhead. This commit therefore add checks for cur_ops types and CONFIG_RCU_NOCB_CPU options when nocbs_nthreads is non-zero to avoid unnecessary nocb task creation. Signed-off-by: Zqiang <qiang1.zhang@intel.com> --- kernel/rcu/rcutorture.c | 6 ++++++ 1 file changed, 6 insertions(+)