The users of idle injection framework allow 100% idle injection. For
example: thermal/cpuidle_cooling.c driver. When the ratio set to 100%,
the runtime_duration becomes zero.
In the function idle_inject_set_duration() in idle injection framework
run_duration_us == 0 is silently ignored, without any error (it is a
void function). So, the caller will assume that everything is fine and
100% idle is effective. But in reality the idle inject will be whatever
set before.
There are two options:
- The caller change their max state to 99% instead of 100% and
document that 100% is not supported by idle inject framework
- Support 100% idle support in idle inject framework
Since there are other protections via RT throttling, this framework can
allow 100% idle. The RT throttling will be activated at 95% idle by
default. The caller disabling RT throttling and injecting 100% idle,
should be aware that CPU can't be used at all.
The idle inject timer is started for (run_duration_us + idle_duration_us)
duration. Hence replace (run_duration_us && idle_duration_us) with
(run_duration_us + idle_duration_us) in the function
idle_inject_set_duration(). Also check for !(run_duration_us +
idle_duration_us) to return -EINVAL in the function idle_inject_start().
Signed-off-by: Srinivas Pandruvada <[email protected]>
---
Change log:
Compared to RFC/RFT
- Add a pr_debug for 100% idle
drivers/powercap/idle_inject.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/powercap/idle_inject.c b/drivers/powercap/idle_inject.c
index c57b40477246..3ac81086d71f 100644
--- a/drivers/powercap/idle_inject.c
+++ b/drivers/powercap/idle_inject.c
@@ -170,10 +170,12 @@ void idle_inject_set_duration(struct idle_inject_device *ii_dev,
unsigned int run_duration_us,
unsigned int idle_duration_us)
{
- if (run_duration_us && idle_duration_us) {
+ if (run_duration_us + idle_duration_us) {
WRITE_ONCE(ii_dev->run_duration_us, run_duration_us);
WRITE_ONCE(ii_dev->idle_duration_us, idle_duration_us);
}
+ if (!run_duration_us)
+ pr_debug("CPU is forced to 100 percent idle\n");
}
EXPORT_SYMBOL_NS_GPL(idle_inject_set_duration, IDLE_INJECT);
@@ -219,7 +221,7 @@ int idle_inject_start(struct idle_inject_device *ii_dev)
unsigned int idle_duration_us = READ_ONCE(ii_dev->idle_duration_us);
unsigned int run_duration_us = READ_ONCE(ii_dev->run_duration_us);
- if (!idle_duration_us || !run_duration_us)
+ if (!(idle_duration_us + run_duration_us))
return -EINVAL;
pr_debug("Starting injecting idle cycles on CPUs '%*pbl'\n",
--
2.31.1
On 17/01/2023 19:22, Srinivas Pandruvada wrote:
> The users of idle injection framework allow 100% idle injection. For
> example: thermal/cpuidle_cooling.c driver. When the ratio set to 100%,
> the runtime_duration becomes zero.
>
> In the function idle_inject_set_duration() in idle injection framework
> run_duration_us == 0 is silently ignored, without any error (it is a
> void function). So, the caller will assume that everything is fine and
> 100% idle is effective. But in reality the idle inject will be whatever
> set before.
>
> There are two options:
> - The caller change their max state to 99% instead of 100% and
> document that 100% is not supported by idle inject framework
> - Support 100% idle support in idle inject framework
>
> Since there are other protections via RT throttling, this framework can
> allow 100% idle. The RT throttling will be activated at 95% idle by
> default. The caller disabling RT throttling and injecting 100% idle,
> should be aware that CPU can't be used at all.
>
> The idle inject timer is started for (run_duration_us + idle_duration_us)
> duration. Hence replace (run_duration_us && idle_duration_us) with
> (run_duration_us + idle_duration_us) in the function
> idle_inject_set_duration(). Also check for !(run_duration_us +
> idle_duration_us) to return -EINVAL in the function idle_inject_start().
>
> Signed-off-by: Srinivas Pandruvada <[email protected]>
> ---
Acked-by: Daniel Lezcano <[email protected]>
--
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It's powercap/idle_inject.
On Tue, Jan 17, 2023 at 7:23 PM Srinivas Pandruvada
<[email protected]> wrote:
>
> The users of idle injection framework allow 100% idle injection. For
> example: thermal/cpuidle_cooling.c driver. When the ratio set to 100%,
> the runtime_duration becomes zero.
>
> In the function idle_inject_set_duration() in idle injection framework
> run_duration_us == 0 is silently ignored, without any error (it is a
> void function). So, the caller will assume that everything is fine and
> 100% idle is effective. But in reality the idle inject will be whatever
> set before.
>
> There are two options:
> - The caller change their max state to 99% instead of 100% and
> document that 100% is not supported by idle inject framework
> - Support 100% idle support in idle inject framework
>
> Since there are other protections via RT throttling, this framework can
> allow 100% idle. The RT throttling will be activated at 95% idle by
> default. The caller disabling RT throttling and injecting 100% idle,
> should be aware that CPU can't be used at all.
>
> The idle inject timer is started for (run_duration_us + idle_duration_us)
> duration. Hence replace (run_duration_us && idle_duration_us) with
> (run_duration_us + idle_duration_us) in the function
> idle_inject_set_duration(). Also check for !(run_duration_us +
> idle_duration_us) to return -EINVAL in the function idle_inject_start().
And I have edited the changelog somewhat.
> Signed-off-by: Srinivas Pandruvada <[email protected]>
> ---
> Change log:
> Compared to RFC/RFT
> - Add a pr_debug for 100% idle
>
> drivers/powercap/idle_inject.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/powercap/idle_inject.c b/drivers/powercap/idle_inject.c
> index c57b40477246..3ac81086d71f 100644
> --- a/drivers/powercap/idle_inject.c
> +++ b/drivers/powercap/idle_inject.c
> @@ -170,10 +170,12 @@ void idle_inject_set_duration(struct idle_inject_device *ii_dev,
> unsigned int run_duration_us,
> unsigned int idle_duration_us)
> {
> - if (run_duration_us && idle_duration_us) {
> + if (run_duration_us + idle_duration_us) {
> WRITE_ONCE(ii_dev->run_duration_us, run_duration_us);
> WRITE_ONCE(ii_dev->idle_duration_us, idle_duration_us);
> }
> + if (!run_duration_us)
> + pr_debug("CPU is forced to 100 percent idle\n");
> }
> EXPORT_SYMBOL_NS_GPL(idle_inject_set_duration, IDLE_INJECT);
>
> @@ -219,7 +221,7 @@ int idle_inject_start(struct idle_inject_device *ii_dev)
> unsigned int idle_duration_us = READ_ONCE(ii_dev->idle_duration_us);
> unsigned int run_duration_us = READ_ONCE(ii_dev->run_duration_us);
>
> - if (!idle_duration_us || !run_duration_us)
> + if (!(idle_duration_us + run_duration_us))
> return -EINVAL;
>
> pr_debug("Starting injecting idle cycles on CPUs '%*pbl'\n",
> --
Applied as 6.3 material, thanks!