2023-02-03 01:35:38

by Zqiang

Subject: [PATCH v3] rcutorture: Create nocb tasks only for CONFIG_RCU_NOCB_CPU=y kernels

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 for CONFIG_RCU_NOCB_CPU=n
kernel, the rcu_nocb_cpu_offload/deoffload() is a no-op and this is also
meaningless for torture_type is non-rcu.

This commit therefore add member can_nocbs_toggle to rcu_torture_ops
structure to avoid unnecessary nocb tasks creation.

Signed-off-by: Zqiang <[email protected]>
---
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

2023-02-03 06:43:27

by Zqiang

Subject: RE: [PATCH v3] rcutorture: Create nocb tasks only for CONFIG_RCU_NOCB_CPU=y kernels

>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 for CONFIG_RCU_NOCB_CPU=n
>kernel, the rcu_nocb_cpu_offload/deoffload() is a no-op and this is also
>meaningless for torture_type is non-rcu.
>
>This commit therefore add member can_nocbs_toggle to rcu_torture_ops
>structure to avoid unnecessary nocb tasks creation.

Will change commit log next version.

Thanks
Zqiang

>
>Signed-off-by: Zqiang <[email protected]>
>---
> 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

2023-02-03 17:28:44

by Joel Fernandes

Subject: Re: [PATCH v3] rcutorture: Create nocb tasks only for CONFIG_RCU_NOCB_CPU=y kernels

On Thu, Feb 2, 2023 at 8:35 PM Zqiang <[email protected]> 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 for CONFIG_RCU_NOCB_CPU=n
> kernel, the rcu_nocb_cpu_offload/deoffload() is a no-op and this is also
> meaningless for torture_type is non-rcu.
>
> This commit therefore add member can_nocbs_toggle to rcu_torture_ops
> structure to avoid unnecessary nocb tasks creation.
>
> Signed-off-by: Zqiang <[email protected]>

Reviewed-by: Joel Fernandes (Google) <[email protected]>

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
>