| Message ID | 1472114562-2736-2-git-send-email-alex.shi@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
Hi, Is there any concern on this patch? Regards Alex On 08/25/2016 04:42 PM, Alex Shi wrote: > The cpu-dma PM QoS constraint impacts all the cpus in the system. There > is no way to let the user to choose a PM QoS constraint per cpu. > > The following patch exposes to the userspace a per cpu based sysfs file > in order to let the userspace to change the value of the PM QoS latency > constraint. > > This change is inoperative in its form and the cpuidle governors have to > take into account the per cpu latency constraint in addition to the > global cpu-dma latency constraint in order to operate properly. > > BTW > The pm_qos_resume_latency usage defined in > Documentation/ABI/testing/sysfs-devices-power > The /sys/devices/.../power/pm_qos_resume_latency_us attribute > contains the PM QoS resume latency limit for the given device, > which is the maximum allowed time it can take to resume the > device, after it has been suspended at run time, from a resume > request to the moment the device will be ready to process I/O, > in microseconds. If it is equal to 0, however, this means that > the PM QoS resume latency may be arbitrary. > > Signed-off-by: Alex Shi <alex.shi@linaro.org> > To: linux-kernel@vger.kernel.org > To: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: linux-pm@vger.kernel.org > Cc: Ulf Hansson <ulf.hansson@linaro.org> > Cc: Daniel Lezcano <daniel.lezcano@linaro.org> > --- > drivers/base/cpu.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c > index 4c28e1a..ba11e23 100644 > --- a/drivers/base/cpu.c > +++ b/drivers/base/cpu.c > @@ -17,6 +17,7 @@ > #include <linux/of.h> > #include <linux/cpufeature.h> > #include <linux/tick.h> > +#include <linux/pm_qos.h> > > #include "base.h" > > @@ -376,6 +377,8 @@ int register_cpu(struct cpu *cpu, int num) > > per_cpu(cpu_sys_devices, num) = &cpu->dev; > register_cpu_under_node(num, cpu_to_node(num)); > + if (dev_pm_qos_expose_latency_limit(&cpu->dev, 0)) > + pr_debug("CPU%d: add resume latency failed\n", num); > > return 0; > } >
Cc Rafael, This patchset is quit simple and straight. Is there any concern or hesitate on it? Thanks Alex On 09/01/2016 11:50 AM, Alex Shi wrote: > > Few commits and patch changed according to Greg's comments. > > Regards > Alex > > ==== > > From 186c534b0b8b9649fbfce05b0b4f90f764c571a4 Mon Sep 17 00:00:00 2001 > From: Alex Shi <alex.shi@linaro.org> > Date: Tue, 16 Aug 2016 15:29:01 +0800 > Subject: [PATCH 2/4] cpu: expose pm_qos_resume_latency for each cpu > > Adding /sys/devices/system/cpu/cpux/power/pm_qos_resume_latency_us for > each of cpus. The pm_qos_resume_latency usage defined in > Documentation/ABI/testing/sysfs-devices-power > > The cpu-dma PM QoS constraint impacts all the cpus in the system. There > is no way to let the user to choose a PM QoS constraint per cpu. > > The following patch exposes to the userspace a per cpu based sysfs file > in order to let the userspace to change the value of the PM QoS latency > constraint. > > This change is inoperative in its form and the cpuidle governors have to > take into account the per cpu latency constraint in addition to the > global cpu-dma latency constraint in order to operate properly. > > Signed-off-by: Alex Shi <alex.shi@linaro.org> > To: linux-kernel@vger.kernel.org > To: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: linux-pm@vger.kernel.org > Cc: Ulf Hansson <ulf.hansson@linaro.org> > Cc: Daniel Lezcano <daniel.lezcano@linaro.org> > --- > drivers/base/cpu.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c > index 4c28e1a..2c3b359 100644 > --- a/drivers/base/cpu.c > +++ b/drivers/base/cpu.c > @@ -17,6 +17,7 @@ > #include <linux/of.h> > #include <linux/cpufeature.h> > #include <linux/tick.h> > +#include <linux/pm_qos.h> > > #include "base.h" > > @@ -376,6 +377,7 @@ int register_cpu(struct cpu *cpu, int num) > > per_cpu(cpu_sys_devices, num) = &cpu->dev; > register_cpu_under_node(num, cpu_to_node(num)); > + dev_pm_qos_expose_latency_limit(&cpu->dev, 0); > > return 0; > } >
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c index 4c28e1a..ba11e23 100644 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -17,6 +17,7 @@ #include <linux/of.h> #include <linux/cpufeature.h> #include <linux/tick.h> +#include <linux/pm_qos.h> #include "base.h" @@ -376,6 +377,8 @@ int register_cpu(struct cpu *cpu, int num) per_cpu(cpu_sys_devices, num) = &cpu->dev; register_cpu_under_node(num, cpu_to_node(num)); + if (dev_pm_qos_expose_latency_limit(&cpu->dev, 0)) + pr_debug("CPU%d: add resume latency failed\n", num); return 0; }
The cpu-dma PM QoS constraint impacts all the cpus in the system. There is no way to let the user to choose a PM QoS constraint per cpu. The following patch exposes to the userspace a per cpu based sysfs file in order to let the userspace to change the value of the PM QoS latency constraint. This change is inoperative in its form and the cpuidle governors have to take into account the per cpu latency constraint in addition to the global cpu-dma latency constraint in order to operate properly. BTW The pm_qos_resume_latency usage defined in Documentation/ABI/testing/sysfs-devices-power The /sys/devices/.../power/pm_qos_resume_latency_us attribute contains the PM QoS resume latency limit for the given device, which is the maximum allowed time it can take to resume the device, after it has been suspended at run time, from a resume request to the moment the device will be ready to process I/O, in microseconds. If it is equal to 0, however, this means that the PM QoS resume latency may be arbitrary. Signed-off-by: Alex Shi <alex.shi@linaro.org> To: linux-kernel@vger.kernel.org To: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: linux-pm@vger.kernel.org Cc: Ulf Hansson <ulf.hansson@linaro.org> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> --- drivers/base/cpu.c | 3 +++ 1 file changed, 3 insertions(+) -- 2.8.1.101.g72d917a