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Date: Thu, 11 Jul 2019 14:15:08 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Amit Kucheria <amit.kucheria@...aro.org>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [RFC PATCH] PM: QoS: Get rid of unused flags
On Wed, Jul 10, 2019 at 12:12 PM Amit Kucheria <amit.kucheria@...aro.org> wrote:
>
> The network_latency and network_throughput flags for PM-QoS have not
> found much use in drivers or in userspace since they were introduced.
>
> Commit 4a733ef1bea7 ("mac80211: remove PM-QoS listener") removed the
> only user PM_QOS_NETWORK_LATENCY in the kernel a while ago and there
> don't seem to be any userspace tools using the character device files
> either.
>
> PM_QOS_MEMORY_BANDWIDTH was never even added to the trace events.
>
> Remove all the flags except cpu_dma_latency.
>
> Signed-off-by: Amit Kucheria <amit.kucheria@...aro.org>
I agree with the rationale, but the patch will clash with some PM QoS
changes from Viresh already in linux-next AFAICS. Can you please
rebase it on top of that material?
> ---
> I've looked around for use of /dev/network_throughput and
> /dev/network_bandwidth) and not found any userspace programs that seem to
> use this currently. So this shouldn't be breaking our ABI contract with
> userspace.
>
> Documentation/power/pm_qos_interface.txt | 5 +--
> include/linux/pm_qos.h | 6 ---
> include/trace/events/power.h | 8 +---
> kernel/power/qos.c | 48 ------------------------
> 4 files changed, 4 insertions(+), 63 deletions(-)
>
> diff --git a/Documentation/power/pm_qos_interface.txt b/Documentation/power/pm_qos_interface.txt
> index 19c5f7b1a7bab..ac53ca4ae24e1 100644
> --- a/Documentation/power/pm_qos_interface.txt
> +++ b/Documentation/power/pm_qos_interface.txt
> @@ -5,8 +5,7 @@ performance expectations by drivers, subsystems and user space applications on
> one of the parameters.
>
> Two different PM QoS frameworks are available:
> -1. PM QoS classes for cpu_dma_latency, network_latency, network_throughput,
> -memory_bandwidth.
> +1. PM QoS classes for cpu_dma_latency
> 2. the per-device PM QoS framework provides the API to manage the per-device latency
> constraints and PM QoS flags.
>
> @@ -74,7 +73,7 @@ cleanup of a process, the interface requires the process to register its
> parameter requests in the following way:
>
> To register the default pm_qos target for the specific parameter, the process
> -must open one of /dev/[cpu_dma_latency, network_latency, network_throughput]
> +must open /dev/cpu_dma_latency
>
> As long as the device node is held open that process has a registered
> request on the parameter.
> diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
> index 6ea1ae373d77c..2a3c237b1910d 100644
> --- a/include/linux/pm_qos.h
> +++ b/include/linux/pm_qos.h
> @@ -13,9 +13,6 @@
> enum {
> PM_QOS_RESERVED = 0,
> PM_QOS_CPU_DMA_LATENCY,
> - PM_QOS_NETWORK_LATENCY,
> - PM_QOS_NETWORK_THROUGHPUT,
> - PM_QOS_MEMORY_BANDWIDTH,
>
> /* insert new class ID */
> PM_QOS_NUM_CLASSES,
> @@ -33,9 +30,6 @@ enum pm_qos_flags_status {
> #define PM_QOS_LATENCY_ANY_NS ((s64)PM_QOS_LATENCY_ANY * NSEC_PER_USEC)
>
> #define PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC)
> -#define PM_QOS_NETWORK_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC)
> -#define PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE 0
> -#define PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE 0
> #define PM_QOS_RESUME_LATENCY_DEFAULT_VALUE PM_QOS_LATENCY_ANY
> #define PM_QOS_RESUME_LATENCY_NO_CONSTRAINT PM_QOS_LATENCY_ANY
> #define PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS PM_QOS_LATENCY_ANY_NS
> diff --git a/include/trace/events/power.h b/include/trace/events/power.h
> index f7aece721aed7..7457e238e1b74 100644
> --- a/include/trace/events/power.h
> +++ b/include/trace/events/power.h
> @@ -379,9 +379,7 @@ DECLARE_EVENT_CLASS(pm_qos_request,
>
> TP_printk("pm_qos_class=%s value=%d",
> __print_symbolic(__entry->pm_qos_class,
> - { PM_QOS_CPU_DMA_LATENCY, "CPU_DMA_LATENCY" },
> - { PM_QOS_NETWORK_LATENCY, "NETWORK_LATENCY" },
> - { PM_QOS_NETWORK_THROUGHPUT, "NETWORK_THROUGHPUT" }),
> + { PM_QOS_CPU_DMA_LATENCY, "CPU_DMA_LATENCY" }),
> __entry->value)
> );
>
> @@ -426,9 +424,7 @@ TRACE_EVENT(pm_qos_update_request_timeout,
>
> TP_printk("pm_qos_class=%s value=%d, timeout_us=%ld",
> __print_symbolic(__entry->pm_qos_class,
> - { PM_QOS_CPU_DMA_LATENCY, "CPU_DMA_LATENCY" },
> - { PM_QOS_NETWORK_LATENCY, "NETWORK_LATENCY" },
> - { PM_QOS_NETWORK_THROUGHPUT, "NETWORK_THROUGHPUT" }),
> + { PM_QOS_CPU_DMA_LATENCY, "CPU_DMA_LATENCY" }),
> __entry->value, __entry->timeout_us)
> );
>
> diff --git a/kernel/power/qos.c b/kernel/power/qos.c
> index 33e3febaba53f..9568a2fe7c116 100644
> --- a/kernel/power/qos.c
> +++ b/kernel/power/qos.c
> @@ -78,57 +78,9 @@ static struct pm_qos_object cpu_dma_pm_qos = {
> .name = "cpu_dma_latency",
> };
>
> -static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
> -static struct pm_qos_constraints network_lat_constraints = {
> - .list = PLIST_HEAD_INIT(network_lat_constraints.list),
> - .target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
> - .default_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
> - .no_constraint_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
> - .type = PM_QOS_MIN,
> - .notifiers = &network_lat_notifier,
> -};
> -static struct pm_qos_object network_lat_pm_qos = {
> - .constraints = &network_lat_constraints,
> - .name = "network_latency",
> -};
> -
> -
> -static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
> -static struct pm_qos_constraints network_tput_constraints = {
> - .list = PLIST_HEAD_INIT(network_tput_constraints.list),
> - .target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
> - .default_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
> - .no_constraint_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
> - .type = PM_QOS_MAX,
> - .notifiers = &network_throughput_notifier,
> -};
> -static struct pm_qos_object network_throughput_pm_qos = {
> - .constraints = &network_tput_constraints,
> - .name = "network_throughput",
> -};
> -
> -
> -static BLOCKING_NOTIFIER_HEAD(memory_bandwidth_notifier);
> -static struct pm_qos_constraints memory_bw_constraints = {
> - .list = PLIST_HEAD_INIT(memory_bw_constraints.list),
> - .target_value = PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE,
> - .default_value = PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE,
> - .no_constraint_value = PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE,
> - .type = PM_QOS_SUM,
> - .notifiers = &memory_bandwidth_notifier,
> -};
> -static struct pm_qos_object memory_bandwidth_pm_qos = {
> - .constraints = &memory_bw_constraints,
> - .name = "memory_bandwidth",
> -};
> -
> -
> static struct pm_qos_object *pm_qos_array[] = {
> &null_pm_qos,
> &cpu_dma_pm_qos,
> - &network_lat_pm_qos,
> - &network_throughput_pm_qos,
> - &memory_bandwidth_pm_qos,
> };
>
> static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
> --
> 2.17.1
>
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