Re: [PATCH v10 1/2] power: introduce PM QoS API on CPU wide

["lihuisong (C)" <lihuisong@huawei.com>]

Hi Konstantin Ananyev,

Thanks for your review.

在 2024/10/14 16:29, Konstantin Ananyev 写道:
>> The deeper the idle state, the lower the power consumption, but the longer
>> the resume time. Some service are delay sensitive and very except the low
>> resume time, like interrupt packet receiving mode.
>>
>> And the "/sys/devices/system/cpu/cpuX/power/pm_qos_resume_latency_us" sysfs
>> interface is used to set and get the resume latency limit on the cpuX for
>> userspace. Each cpuidle governor in Linux select which idle state to enter
>> based on this CPU resume latency in their idle task.
>>
>> The per-CPU PM QoS API can be used to control this CPU's idle state
>> selection and limit just enter the shallowest idle state to low the delay
>> after sleep by setting strict resume latency (zero value).
>>
>> Signed-off-by: Huisong Li <lihuisong@huawei.com>
>> Acked-by: Morten Brørup <mb@smartsharesystems.com>
>> ---
>>   doc/guides/prog_guide/power_man.rst    |  24 ++++++
>>   doc/guides/rel_notes/release_24_11.rst |   5 ++
>>   lib/power/meson.build                  |   2 +
>>   lib/power/rte_power_qos.c              | 111 +++++++++++++++++++++++++
>>   lib/power/rte_power_qos.h              |  73 ++++++++++++++++
>>   lib/power/version.map                  |   4 +
>>   6 files changed, 219 insertions(+)
>>   create mode 100644 lib/power/rte_power_qos.c
>>   create mode 100644 lib/power/rte_power_qos.h
>>
>> diff --git a/doc/guides/prog_guide/power_man.rst b/doc/guides/prog_guide/power_man.rst
>> index f6674efe2d..faa32b4320 100644
>> --- a/doc/guides/prog_guide/power_man.rst
>> +++ b/doc/guides/prog_guide/power_man.rst
>> @@ -249,6 +249,30 @@ Get Num Pkgs
>>   Get Num Dies
>>     Get the number of die's on a given package.
>>
>> +
>> +PM QoS
>> +------
>> +
>> +The deeper the idle state, the lower the power consumption, but the longer
>> +the resume time. Some service are delay sensitive and very except the low
>> +resume time, like interrupt packet receiving mode.
>> +
>> +And the "/sys/devices/system/cpu/cpuX/power/pm_qos_resume_latency_us" sysfs
>> +interface is used to set and get the resume latency limit on the cpuX for
>> +userspace. Each cpuidle governor in Linux select which idle state to enter
>> +based on this CPU resume latency in their idle task.
>> +
>> +The per-CPU PM QoS API can be used to set and get the CPU resume latency based
>> +on this sysfs.
>> +
>> +The ``rte_power_qos_set_cpu_resume_latency()`` function can control the CPU's
>> +idle state selection in Linux and limit just to enter the shallowest idle state
>> +to low the delay of resuming service after sleeping by setting strict resume
>> +latency (zero value).
>> +
>> +The ``rte_power_qos_get_cpu_resume_latency()`` function can get the resume
>> +latency on specified CPU.
>> +
>>   References
>>   ----------
>>
>> diff --git a/doc/guides/rel_notes/release_24_11.rst b/doc/guides/rel_notes/release_24_11.rst
>> index 0ff70d9057..bd72d0a595 100644
>> --- a/doc/guides/rel_notes/release_24_11.rst
>> +++ b/doc/guides/rel_notes/release_24_11.rst
>> @@ -55,6 +55,11 @@ New Features
>>        Also, make sure to start the actual text at the margin.
>>        =======================================================
>>
>> +* **Introduce per-CPU PM QoS interface.**
>> +
>> +  * Add per-CPU PM QoS interface to low the delay after sleep by controlling
>> +    CPU idle state selection.
>> +
>>
>>   Removed Items
>>   -------------
>> diff --git a/lib/power/meson.build b/lib/power/meson.build
>> index b8426589b2..8222e178b0 100644
>> --- a/lib/power/meson.build
>> +++ b/lib/power/meson.build
>> @@ -23,12 +23,14 @@ sources = files(
>>           'rte_power.c',
>>           'rte_power_uncore.c',
>>           'rte_power_pmd_mgmt.c',
>> +        'rte_power_qos.c',
>>   )
>>   headers = files(
>>           'rte_power.h',
>>           'rte_power_guest_channel.h',
>>           'rte_power_pmd_mgmt.h',
>>           'rte_power_uncore.h',
>> +        'rte_power_qos.h',
>>   )
>>   if cc.has_argument('-Wno-cast-qual')
>>       cflags += '-Wno-cast-qual'
>> diff --git a/lib/power/rte_power_qos.c b/lib/power/rte_power_qos.c
>> new file mode 100644
>> index 0000000000..8eb26cd41a
>> --- /dev/null
>> +++ b/lib/power/rte_power_qos.c
>> @@ -0,0 +1,111 @@
>> +/* SPDX-License-Identifier: BSD-3-Clause
>> + * Copyright(c) 2024 HiSilicon Limited
>> + */
>> +
>> +#include <errno.h>
>> +#include <stdlib.h>
>> +#include <string.h>
>> +
>> +#include <rte_lcore.h>
>> +#include <rte_log.h>
>> +
>> +#include "power_common.h"
>> +#include "rte_power_qos.h"
>> +
>> +#define PM_QOS_SYSFILE_RESUME_LATENCY_US	\
>> +	"/sys/devices/system/cpu/cpu%u/power/pm_qos_resume_latency_us"
>> +
>> +#define PM_QOS_CPU_RESUME_LATENCY_BUF_LEN	32
>> +
>> +int
>> +rte_power_qos_set_cpu_resume_latency(uint16_t lcore_id, int latency)
>> +{
>> +	char buf[PM_QOS_CPU_RESUME_LATENCY_BUF_LEN];
>> +	FILE *f;
>> +	int ret;
>> +
>> +	if (!rte_lcore_is_enabled(lcore_id)) {
>> +		POWER_LOG(ERR, "lcore id %u is not enabled", lcore_id);
>> +		return -EINVAL;
>> +	}
>> +
>> +	if (latency < 0) {
>> +		POWER_LOG(ERR, "latency should be greater than and equal to 0");
>> +		return -EINVAL;
>> +	}
>> +
>> +	ret = open_core_sysfs_file(&f, "w", PM_QOS_SYSFILE_RESUME_LATENCY_US, lcore_id);
> That was already brought by Morten:
> lcore_id is not always equal to cpu_core_id (cpu affinity).
Yes, Morten also mentioned it.
And I tried to answer him, please find our previous disscussion, thanks.
I think it's ok😁
> Looking through power library it is not specific to that particular patch,
> but sort of common limitation (bug?) in rte_power lib.
Yes it is very common in power lib.
>   
>
>> +	if (ret != 0) {
>> +		POWER_LOG(ERR, "Failed to open "PM_QOS_SYSFILE_RESUME_LATENCY_US, lcore_id);
>> +		return ret;
>> +	}
>> +
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