Messages in this thread Patch in this message | | | From | Srinivas Pandruvada <> | Subject | [PATCH] thermal/idle_inject: Support 100% idle injection | Date | Tue, 17 Jan 2023 10:22:40 -0800 |
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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 <srinivas.pandruvada@linux.intel.com> --- 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
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