[PATCH] cpuidle: mvebu: update cpuidle thresholds for Armada XP SOCs

[PATCH] cpuidle: mvebu: update cpuidle thresholds for Armada XP SOCs

[s. rannou]

Originally, the thresholds used in the cpuidle driver for Armada SOCs
were temporarily chosen, leaving room for improvements.

This commit updates the thresholds for the Armada XP SOCs with values
that positively impact performances:

                                without patch  with patch   vendor kernel
 - iperf localhost (gbit/sec)   ~3.7           ~6.4         ~5.4
 - ioping tmpfs (iops)          ~163k          ~206k        ~179k
 - ioping tmpfs (mib/s)         ~636           ~805         ~699

The idle power consumption is negatively impacted (proportionally less
than the performance gain), and we are still performing better than
the vendor kernel here:

                                without patch   with patch  vendor kernel
 - power consumption idle (W)   ~2.4            ~3.2        ~4.4
 - power consumption busy (W)   ~8.6            ~8.3        ~8.6

There is still room for improvement regarding the value of these
thresholds, they were chosen to mimic the vendor kernel.

This patch only impacts Armada XP SOCs and was tested on Online Labs
C1 boards. A similar approach can be taken to improve the performances
of the Armada 370 and Armada 38x SOCs.

Thanks a lot to Thomas Petazzoni, Gregory Clement and Willy Tarreau
for the discussions and tips around this topic.

Signed-off-by: Sebastien Rannou <mxs@sbrk.org>
---
 drivers/cpuidle/cpuidle-mvebu-v7.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-mvebu-v7.c b/drivers/cpuidle/cpuidle-mvebu-v7.c
index 38e6861..3716a1f 100644
--- a/drivers/cpuidle/cpuidle-mvebu-v7.c
+++ b/drivers/cpuidle/cpuidle-mvebu-v7.c
@@ -50,17 +50,17 @@ static struct cpuidle_driver armadaxp_idle_driver = {
 	.states[0]		= ARM_CPUIDLE_WFI_STATE,
 	.states[1]		= {
 		.enter			= mvebu_v7_enter_idle,
-		.exit_latency		= 10,
+		.exit_latency		= 100,
 		.power_usage		= 50,
-		.target_residency	= 100,
+		.target_residency	= 1000,
 		.name			= "MV CPU IDLE",
 		.desc			= "CPU power down",
 	},
 	.states[2]		= {
 		.enter			= mvebu_v7_enter_idle,
-		.exit_latency		= 100,
+		.exit_latency		= 1000,
 		.power_usage		= 5,
-		.target_residency	= 1000,
+		.target_residency	= 10000,
 		.flags			= MVEBU_V7_FLAG_DEEP_IDLE,
 		.name			= "MV CPU DEEP IDLE",
 		.desc			= "CPU and L2 Fabric power down",
-- 
2.1.4

[PATCH] cpuidle: mvebu: update cpuidle thresholds for Armada XP SOCs

[Gregory CLEMENT]

Hi Sebastien,

On 13/02/2015 15:55, s. rannou wrote:
> Originally, the thresholds used in the cpuidle driver for Armada SOCs
> were temporarily chosen, leaving room for improvements.
> 
> This commit updates the thresholds for the Armada XP SOCs with values
> that positively impact performances:
> 
>                                 without patch  with patch   vendor kernel
>  - iperf localhost (gbit/sec)   ~3.7           ~6.4         ~5.4
>  - ioping tmpfs (iops)          ~163k          ~206k        ~179k
>  - ioping tmpfs (mib/s)         ~636           ~805         ~699
> 
> The idle power consumption is negatively impacted (proportionally less
> than the performance gain), and we are still performing better than
> the vendor kernel here:
> 
>                                 without patch   with patch  vendor kernel
>  - power consumption idle (W)   ~2.4            ~3.2        ~4.4
>  - power consumption busy (W)   ~8.6            ~8.3        ~8.6
> 
> There is still room for improvement regarding the value of these
> thresholds, they were chosen to mimic the vendor kernel.
> 
> This patch only impacts Armada XP SOCs and was tested on Online Labs
> C1 boards. A similar approach can be taken to improve the performances
> of the Armada 370 and Armada 38x SOCs.
> 
> Thanks a lot to Thomas Petazzoni, Gregory Clement and Willy Tarreau
> for the discussions and tips around this topic.

Thanks for your work and all the test you have done. As you mentioned
there should be still room for improvement, but this patch is already
a step in the good direction. So you can add my:

Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>

While this driver is related to mvebu SoCs, it is not part of the mvebu subsystem
but of the PM subsystem and should be taken by its maintainers. I added them
in copy as well as the pm list.

Daniel and Rafael,
if you didn't get the original email I can bounced if needed. I also wonder
it it would worth applying it on the stable branch. What do you think about it?

Thanks,

Gregory



> 
> Signed-off-by: Sebastien Rannou <mxs@sbrk.org>
> ---
>  drivers/cpuidle/cpuidle-mvebu-v7.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/cpuidle/cpuidle-mvebu-v7.c b/drivers/cpuidle/cpuidle-mvebu-v7.c
> index 38e6861..3716a1f 100644
> --- a/drivers/cpuidle/cpuidle-mvebu-v7.c
> +++ b/drivers/cpuidle/cpuidle-mvebu-v7.c
> @@ -50,17 +50,17 @@ static struct cpuidle_driver armadaxp_idle_driver = {
>  	.states[0]		= ARM_CPUIDLE_WFI_STATE,
>  	.states[1]		= {
>  		.enter			= mvebu_v7_enter_idle,
> -		.exit_latency		= 10,
> +		.exit_latency		= 100,
>  		.power_usage		= 50,
> -		.target_residency	= 100,
> +		.target_residency	= 1000,
>  		.name			= "MV CPU IDLE",
>  		.desc			= "CPU power down",
>  	},
>  	.states[2]		= {
>  		.enter			= mvebu_v7_enter_idle,
> -		.exit_latency		= 100,
> +		.exit_latency		= 1000,
>  		.power_usage		= 5,
> -		.target_residency	= 1000,
> +		.target_residency	= 10000,
>  		.flags			= MVEBU_V7_FLAG_DEEP_IDLE,
>  		.name			= "MV CPU DEEP IDLE",
>  		.desc			= "CPU and L2 Fabric power down",
> 


-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

[PATCH] cpuidle: mvebu: update cpuidle thresholds for Armada XP SOCs

[Daniel Lezcano]

On 02/13/2015 03:55 PM, s. rannou wrote:
> Originally, the thresholds used in the cpuidle driver for Armada SOCs
> were temporarily chosen, leaving room for improvements.
>
> This commit updates the thresholds for the Armada XP SOCs with values
> that positively impact performances:
>
>                                  without patch  with patch   vendor kernel
>   - iperf localhost (gbit/sec)   ~3.7           ~6.4         ~5.4
>   - ioping tmpfs (iops)          ~163k          ~206k        ~179k
>   - ioping tmpfs (mib/s)         ~636           ~805         ~699
>
> The idle power consumption is negatively impacted (proportionally less
> than the performance gain), and we are still performing better than
> the vendor kernel here:
>
>                                  without patch   with patch  vendor kernel
>   - power consumption idle (W)   ~2.4            ~3.2        ~4.4
>   - power consumption busy (W)   ~8.6            ~8.3        ~8.6
>
> There is still room for improvement regarding the value of these
> thresholds, they were chosen to mimic the vendor kernel.
>
> This patch only impacts Armada XP SOCs and was tested on Online Labs
> C1 boards. A similar approach can be taken to improve the performances
> of the Armada 370 and Armada 38x SOCs.
>
> Thanks a lot to Thomas Petazzoni, Gregory Clement and Willy Tarreau
> for the discussions and tips around this topic.

Hi Sebastien,

trying to tune the target residency and the exit latency is a good idea 
but you can have multiple results. If you increase the exit latency and 
the target residency, then the governor will choose a shallow state, 
thus improving the performance and degrading the power consumption. If 
you reduce the values, then the performance will degrade but the power 
saving will increase in an acceptable interval (until going to this 
state does not consume more energy).

If you have the possibility, I would suggest to apply the right 
methodology to find the right values by using the description in the 
wiki page [1]. If you can access to the energy values to enter / exit 
the state and the power consumed in each idle state, then you can 
mathematically compute the right values.

   -- Daniel

[1] 
https://wiki.linaro.org/WorkingGroups/PowerManagement/Doc/ComputingTargetResidency

>
> Signed-off-by: Sebastien Rannou <mxs@sbrk.org>
> ---
>   drivers/cpuidle/cpuidle-mvebu-v7.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/cpuidle/cpuidle-mvebu-v7.c b/drivers/cpuidle/cpuidle-mvebu-v7.c
> index 38e6861..3716a1f 100644
> --- a/drivers/cpuidle/cpuidle-mvebu-v7.c
> +++ b/drivers/cpuidle/cpuidle-mvebu-v7.c
> @@ -50,17 +50,17 @@ static struct cpuidle_driver armadaxp_idle_driver = {
>   	.states[0]		= ARM_CPUIDLE_WFI_STATE,
>   	.states[1]		= {
>   		.enter			= mvebu_v7_enter_idle,
> -		.exit_latency		= 10,
> +		.exit_latency		= 100,
>   		.power_usage		= 50,
> -		.target_residency	= 100,
> +		.target_residency	= 1000,
>   		.name			= "MV CPU IDLE",
>   		.desc			= "CPU power down",
>   	},
>   	.states[2]		= {
>   		.enter			= mvebu_v7_enter_idle,
> -		.exit_latency		= 100,
> +		.exit_latency		= 1000,
>   		.power_usage		= 5,
> -		.target_residency	= 1000,
> +		.target_residency	= 10000,
>   		.flags			= MVEBU_V7_FLAG_DEEP_IDLE,
>   		.name			= "MV CPU DEEP IDLE",
>   		.desc			= "CPU and L2 Fabric power down",
>


-- 
  <http://www.linaro.org/> Linaro.org ? Open source software for ARM SoCs

Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
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[PATCH] cpuidle: mvebu: update cpuidle thresholds for Armada XP SOCs

[Sebastien Rannou]

Hi Daniel,

Thanks for the explanation and thanks for the link, I wish I had read
it beforehand.

On Wed, 25 Feb 2015, Daniel Lezcano wrote:
> If you have the possibility, I would suggest to apply the right methodology to
> find the right values by using the description in the wiki page [1]. If you
> can access to the energy values to enter / exit the state and the power
> consumed in each idle state, then you can mathematically compute the right
> values.

Unfortunately I don't have access to the cost of transitions between
states, nor do I have the time taken by each transition (which I could
have used to infer the cost). I only have the power consumption of the
different states.

I plan to find the adequate values by testing different combinations,
but it is going to take some efforts before having a second
patch. Since this patch already improves the situation by using the
vendor's values, I think it is a move in the right direction, even
though not being the most adequate values.

[PATCH] cpuidle: mvebu: update cpuidle thresholds for Armada XP SOCs

[Daniel Lezcano]

On 02/25/2015 04:56 PM, Sebastien Rannou wrote:
> Hi Daniel,
>
> Thanks for the explanation and thanks for the link, I wish I had read
> it beforehand.
>
> On Wed, 25 Feb 2015, Daniel Lezcano wrote:
>> If you have the possibility, I would suggest to apply the right methodology to
>> find the right values by using the description in the wiki page [1]. If you
>> can access to the energy values to enter / exit the state and the power
>> consumed in each idle state, then you can mathematically compute the right
>> values.
>
> Unfortunately I don't have access to the cost of transitions between
> states, nor do I have the time taken by each transition (which I could
> have used to infer the cost). I only have the power consumption of the
> different states.

If you have the consumption for the different idle state + running, you 
have 60% of the data :)

> I plan to find the adequate values by testing different combinations,
> but it is going to take some efforts before having a second
> patch.

You may waste your time because of the non deterministic prediction. 
Sometimes you will test with right values but wrong prediction and a 
cache 50% filled, sometimes you will test with wrong values and wrong 
prediction but a cache 20% filled etc ...

The only way to measure accurately is to identify the cpu power rails 
and measure the current peak when entering/exiting the different idle 
states with a device (oscilloscope, or whatever).

> Since this patch already improves the situation by using the
> vendor's values, I think it is a move in the right direction, even
> though not being the most adequate values.

Just to clarify, vendor's values are from an out-of-tree which means it 
does not exist from an opensource pov and hence does not enter in the 
equation to pick the patch or not.

Regarding the values you measured for perf and power, it appears we have 
a improvement in terms of performance but with a power consumption 
degradation.

I am not against this patch, but I would like to have the ack from 
another Armada maintainer (Jason, Andrew or Sebastian) to be sure this 
trade-off is accepted.

Thanks

   -- Daniel

-- 
  <http://www.linaro.org/> Linaro.org ? Open source software for ARM SoCs

Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
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[PATCH] cpuidle: mvebu: update cpuidle thresholds for Armada XP SOCs

[Thomas Petazzoni]

Hello Daniel,

I know you suggested a more rigorous method of determining the exit
latency and target residency times, but would it be nonetheless
possible to apply this patch, which clearly improves performance a lot,
and actually makes the code match the values used in the vendor kernel?

I also think this patch should be marked for stable, it fixes values
introduced in commit b858fbc1919720f7f54360098ece03b383e961fa, and
should therefore be backported all the way to v3.16.

Thanks a lot,

Thomas

On Fri, 13 Feb 2015 15:55:03 +0100 (CET), s. rannou wrote:
> Originally, the thresholds used in the cpuidle driver for Armada SOCs
> were temporarily chosen, leaving room for improvements.
> 
> This commit updates the thresholds for the Armada XP SOCs with values
> that positively impact performances:
> 
>                                 without patch  with patch   vendor kernel
>  - iperf localhost (gbit/sec)   ~3.7           ~6.4         ~5.4
>  - ioping tmpfs (iops)          ~163k          ~206k        ~179k
>  - ioping tmpfs (mib/s)         ~636           ~805         ~699
> 
> The idle power consumption is negatively impacted (proportionally less
> than the performance gain), and we are still performing better than
> the vendor kernel here:
> 
>                                 without patch   with patch  vendor kernel
>  - power consumption idle (W)   ~2.4            ~3.2        ~4.4
>  - power consumption busy (W)   ~8.6            ~8.3        ~8.6
> 
> There is still room for improvement regarding the value of these
> thresholds, they were chosen to mimic the vendor kernel.
> 
> This patch only impacts Armada XP SOCs and was tested on Online Labs
> C1 boards. A similar approach can be taken to improve the performances
> of the Armada 370 and Armada 38x SOCs.
> 
> Thanks a lot to Thomas Petazzoni, Gregory Clement and Willy Tarreau
> for the discussions and tips around this topic.
> 
> Signed-off-by: Sebastien Rannou <mxs@sbrk.org>
> ---
>  drivers/cpuidle/cpuidle-mvebu-v7.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/cpuidle/cpuidle-mvebu-v7.c b/drivers/cpuidle/cpuidle-mvebu-v7.c
> index 38e6861..3716a1f 100644
> --- a/drivers/cpuidle/cpuidle-mvebu-v7.c
> +++ b/drivers/cpuidle/cpuidle-mvebu-v7.c
> @@ -50,17 +50,17 @@ static struct cpuidle_driver armadaxp_idle_driver = {
>  	.states[0]		= ARM_CPUIDLE_WFI_STATE,
>  	.states[1]		= {
>  		.enter			= mvebu_v7_enter_idle,
> -		.exit_latency		= 10,
> +		.exit_latency		= 100,
>  		.power_usage		= 50,
> -		.target_residency	= 100,
> +		.target_residency	= 1000,
>  		.name			= "MV CPU IDLE",
>  		.desc			= "CPU power down",
>  	},
>  	.states[2]		= {
>  		.enter			= mvebu_v7_enter_idle,
> -		.exit_latency		= 100,
> +		.exit_latency		= 1000,
>  		.power_usage		= 5,
> -		.target_residency	= 1000,
> +		.target_residency	= 10000,
>  		.flags			= MVEBU_V7_FLAG_DEEP_IDLE,
>  		.name			= "MV CPU DEEP IDLE",
>  		.desc			= "CPU and L2 Fabric power down",



-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[PATCH] cpuidle: mvebu: update cpuidle thresholds for Armada XP SOCs

[Daniel Lezcano]

On 03/10/2015 07:05 PM, Thomas Petazzoni wrote:
> Hello Daniel,
>
> I know you suggested a more rigorous method of determining the exit
> latency and target residency times, but would it be nonetheless
> possible to apply this patch, which clearly improves performance a lot,
> and actually makes the code match the values used in the vendor kernel?
>
> I also think this patch should be marked for stable, it fixes values
> introduced in commit b858fbc1919720f7f54360098ece03b383e961fa, and
> should therefore be backported all the way to v3.16.

I don't have a problem to apply this patch. But I would like to have 
confirmation from one of the Armada maintainers the tradeoff is accepted 
(less energy saving for more performance).


> On Fri, 13 Feb 2015 15:55:03 +0100 (CET), s. rannou wrote:
>> Originally, the thresholds used in the cpuidle driver for Armada SOCs
>> were temporarily chosen, leaving room for improvements.
>>
>> This commit updates the thresholds for the Armada XP SOCs with values
>> that positively impact performances:
>>
>>                                  without patch  with patch   vendor kernel
>>   - iperf localhost (gbit/sec)   ~3.7           ~6.4         ~5.4
>>   - ioping tmpfs (iops)          ~163k          ~206k        ~179k
>>   - ioping tmpfs (mib/s)         ~636           ~805         ~699
>>
>> The idle power consumption is negatively impacted (proportionally less
>> than the performance gain), and we are still performing better than
>> the vendor kernel here:
>>
>>                                  without patch   with patch  vendor kernel
>>   - power consumption idle (W)   ~2.4            ~3.2        ~4.4
>>   - power consumption busy (W)   ~8.6            ~8.3        ~8.6
>>
>> There is still room for improvement regarding the value of these
>> thresholds, they were chosen to mimic the vendor kernel.
>>
>> This patch only impacts Armada XP SOCs and was tested on Online Labs
>> C1 boards. A similar approach can be taken to improve the performances
>> of the Armada 370 and Armada 38x SOCs.
>>
>> Thanks a lot to Thomas Petazzoni, Gregory Clement and Willy Tarreau
>> for the discussions and tips around this topic.
>>
>> Signed-off-by: Sebastien Rannou <mxs@sbrk.org>
>> ---
>>   drivers/cpuidle/cpuidle-mvebu-v7.c | 8 ++++----
>>   1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/cpuidle/cpuidle-mvebu-v7.c b/drivers/cpuidle/cpuidle-mvebu-v7.c
>> index 38e6861..3716a1f 100644
>> --- a/drivers/cpuidle/cpuidle-mvebu-v7.c
>> +++ b/drivers/cpuidle/cpuidle-mvebu-v7.c
>> @@ -50,17 +50,17 @@ static struct cpuidle_driver armadaxp_idle_driver = {
>>   	.states[0]		= ARM_CPUIDLE_WFI_STATE,
>>   	.states[1]		= {
>>   		.enter			= mvebu_v7_enter_idle,
>> -		.exit_latency		= 10,
>> +		.exit_latency		= 100,
>>   		.power_usage		= 50,
>> -		.target_residency	= 100,
>> +		.target_residency	= 1000,
>>   		.name			= "MV CPU IDLE",
>>   		.desc			= "CPU power down",
>>   	},
>>   	.states[2]		= {
>>   		.enter			= mvebu_v7_enter_idle,
>> -		.exit_latency		= 100,
>> +		.exit_latency		= 1000,
>>   		.power_usage		= 5,
>> -		.target_residency	= 1000,
>> +		.target_residency	= 10000,
>>   		.flags			= MVEBU_V7_FLAG_DEEP_IDLE,
>>   		.name			= "MV CPU DEEP IDLE",
>>   		.desc			= "CPU and L2 Fabric power down",
>
>
>


-- 
  <http://www.linaro.org/> Linaro.org ? Open source software for ARM SoCs

Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
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[PATCH] cpuidle: mvebu: update cpuidle thresholds for Armada XP SOCs

[Andrew Lunn]

On Tue, Mar 10, 2015 at 07:35:19PM +0100, Daniel Lezcano wrote:
> On 03/10/2015 07:05 PM, Thomas Petazzoni wrote:
> >Hello Daniel,
> >
> >I know you suggested a more rigorous method of determining the exit
> >latency and target residency times, but would it be nonetheless
> >possible to apply this patch, which clearly improves performance a lot,
> >and actually makes the code match the values used in the vendor kernel?
> >
> >I also think this patch should be marked for stable, it fixes values
> >introduced in commit b858fbc1919720f7f54360098ece03b383e961fa, and
> >should therefore be backported all the way to v3.16.
> 
> I don't have a problem to apply this patch. But I would like to have
> confirmation from one of the Armada maintainers the tradeoff is
> accepted (less energy saving for more performance).

Hi Daniel

I believe Gregory has already acked this patch. Or do you want a 
explicit Acked-and-tradeoff-accepted-by: 

	 Andrew

[PATCH] cpuidle: mvebu: update cpuidle thresholds for Armada XP SOCs

[Gregory CLEMENT]

Le 10 mars 2015 19:35:19 GMT+01:00, Daniel Lezcano <daniel.lezcano@linaro.org> a ?crit :
>On 03/10/2015 07:05 PM, Thomas Petazzoni wrote:
>> Hello Daniel,
>>
>> I know you suggested a more rigorous method of determining the exit
>> latency and target residency times, but would it be nonetheless
>> possible to apply this patch, which clearly improves performance a
>lot,
>> and actually makes the code match the values used in the vendor
>kernel?
>>
>> I also think this patch should be marked for stable, it fixes values
>> introduced in commit b858fbc1919720f7f54360098ece03b383e961fa, and
>> should therefore be backported all the way to v3.16.
>
>I don't have a problem to apply this patch. But I would like to have 
>confirmation from one of the Armada maintainers the tradeoff is
>accepted 
>(less energy saving for more performance).

Hi Daniel,

I already gave my acked- by for this patch, so for me this tradeoff
is acceptable.

Gr?gory

>
>
>> On Fri, 13 Feb 2015 15:55:03 +0100 (CET), s. rannou wrote:
>>> Originally, the thresholds used in the cpuidle driver for Armada
>SOCs
>>> were temporarily chosen, leaving room for improvements.
>>>
>>> This commit updates the thresholds for the Armada XP SOCs with
>values
>>> that positively impact performances:
>>>
>>>                                  without patch  with patch   vendor
>kernel
>>>   - iperf localhost (gbit/sec)   ~3.7           ~6.4         ~5.4
>>>   - ioping tmpfs (iops)          ~163k          ~206k        ~179k
>>>   - ioping tmpfs (mib/s)         ~636           ~805         ~699
>>>
>>> The idle power consumption is negatively impacted (proportionally
>less
>>> than the performance gain), and we are still performing better than
>>> the vendor kernel here:
>>>
>>>                                  without patch   with patch  vendor
>kernel
>>>   - power consumption idle (W)   ~2.4            ~3.2        ~4.4
>>>   - power consumption busy (W)   ~8.6            ~8.3        ~8.6
>>>
>>> There is still room for improvement regarding the value of these
>>> thresholds, they were chosen to mimic the vendor kernel.
>>>
>>> This patch only impacts Armada XP SOCs and was tested on Online Labs
>>> C1 boards. A similar approach can be taken to improve the
>performances
>>> of the Armada 370 and Armada 38x SOCs.
>>>
>>> Thanks a lot to Thomas Petazzoni, Gregory Clement and Willy Tarreau
>>> for the discussions and tips around this topic.
>>>
>>> Signed-off-by: Sebastien Rannou <mxs@sbrk.org>
>>> ---
>>>   drivers/cpuidle/cpuidle-mvebu-v7.c | 8 ++++----
>>>   1 file changed, 4 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/cpuidle/cpuidle-mvebu-v7.c
>b/drivers/cpuidle/cpuidle-mvebu-v7.c
>>> index 38e6861..3716a1f 100644
>>> --- a/drivers/cpuidle/cpuidle-mvebu-v7.c
>>> +++ b/drivers/cpuidle/cpuidle-mvebu-v7.c
>>> @@ -50,17 +50,17 @@ static struct cpuidle_driver
>armadaxp_idle_driver = {
>>>   	.states[0]		= ARM_CPUIDLE_WFI_STATE,
>>>   	.states[1]		= {
>>>   		.enter			= mvebu_v7_enter_idle,
>>> -		.exit_latency		= 10,
>>> +		.exit_latency		= 100,
>>>   		.power_usage		= 50,
>>> -		.target_residency	= 100,
>>> +		.target_residency	= 1000,
>>>   		.name			= "MV CPU IDLE",
>>>   		.desc			= "CPU power down",
>>>   	},
>>>   	.states[2]		= {
>>>   		.enter			= mvebu_v7_enter_idle,
>>> -		.exit_latency		= 100,
>>> +		.exit_latency		= 1000,
>>>   		.power_usage		= 5,
>>> -		.target_residency	= 1000,
>>> +		.target_residency	= 10000,
>>>   		.flags			= MVEBU_V7_FLAG_DEEP_IDLE,
>>>   		.name			= "MV CPU DEEP IDLE",
>>>   		.desc			= "CPU and L2 Fabric power down",
>>
>>
>>
>
>
>-- 
><http://www.linaro.org/> Linaro.org ? Open source software for ARM SoCs
>
>Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
><http://twitter.com/#!/linaroorg> Twitter |
><http://www.linaro.org/linaro-blog/> Blog


-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

[PATCH] cpuidle: mvebu: update cpuidle thresholds for Armada XP SOCs

[Daniel Lezcano]

On 03/10/2015 07:47 PM, Gregory CLEMENT wrote:
> Le 10 mars 2015 19:35:19 GMT+01:00, Daniel Lezcano <daniel.lezcano@linaro.org> a ?crit :
>> On 03/10/2015 07:05 PM, Thomas Petazzoni wrote:
>>> Hello Daniel,
>>>
>>> I know you suggested a more rigorous method of determining the exit
>>> latency and target residency times, but would it be nonetheless
>>> possible to apply this patch, which clearly improves performance a
>> lot,
>>> and actually makes the code match the values used in the vendor
>> kernel?
>>>
>>> I also think this patch should be marked for stable, it fixes values
>>> introduced in commit b858fbc1919720f7f54360098ece03b383e961fa, and
>>> should therefore be backported all the way to v3.16.
>>
>> I don't have a problem to apply this patch. But I would like to have
>> confirmation from one of the Armada maintainers the tradeoff is
>> accepted
>> (less energy saving for more performance).
>
> Hi Daniel,
>
> I already gave my acked- by for this patch, so for me this tradeoff
> is acceptable.

Ah, Indeed.

Thanks.

   -- Daniel

>>
>>> On Fri, 13 Feb 2015 15:55:03 +0100 (CET), s. rannou wrote:
>>>> Originally, the thresholds used in the cpuidle driver for Armada
>> SOCs
>>>> were temporarily chosen, leaving room for improvements.
>>>>
>>>> This commit updates the thresholds for the Armada XP SOCs with
>> values
>>>> that positively impact performances:
>>>>
>>>>                                   without patch  with patch   vendor
>> kernel
>>>>    - iperf localhost (gbit/sec)   ~3.7           ~6.4         ~5.4
>>>>    - ioping tmpfs (iops)          ~163k          ~206k        ~179k
>>>>    - ioping tmpfs (mib/s)         ~636           ~805         ~699
>>>>
>>>> The idle power consumption is negatively impacted (proportionally
>> less
>>>> than the performance gain), and we are still performing better than
>>>> the vendor kernel here:
>>>>
>>>>                                   without patch   with patch  vendor
>> kernel
>>>>    - power consumption idle (W)   ~2.4            ~3.2        ~4.4
>>>>    - power consumption busy (W)   ~8.6            ~8.3        ~8.6
>>>>
>>>> There is still room for improvement regarding the value of these
>>>> thresholds, they were chosen to mimic the vendor kernel.
>>>>
>>>> This patch only impacts Armada XP SOCs and was tested on Online Labs
>>>> C1 boards. A similar approach can be taken to improve the
>> performances
>>>> of the Armada 370 and Armada 38x SOCs.
>>>>
>>>> Thanks a lot to Thomas Petazzoni, Gregory Clement and Willy Tarreau
>>>> for the discussions and tips around this topic.
>>>>
>>>> Signed-off-by: Sebastien Rannou <mxs@sbrk.org>
>>>> ---
>>>>    drivers/cpuidle/cpuidle-mvebu-v7.c | 8 ++++----
>>>>    1 file changed, 4 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/drivers/cpuidle/cpuidle-mvebu-v7.c
>> b/drivers/cpuidle/cpuidle-mvebu-v7.c
>>>> index 38e6861..3716a1f 100644
>>>> --- a/drivers/cpuidle/cpuidle-mvebu-v7.c
>>>> +++ b/drivers/cpuidle/cpuidle-mvebu-v7.c
>>>> @@ -50,17 +50,17 @@ static struct cpuidle_driver
>> armadaxp_idle_driver = {
>>>>    	.states[0]		= ARM_CPUIDLE_WFI_STATE,
>>>>    	.states[1]		= {
>>>>    		.enter			= mvebu_v7_enter_idle,
>>>> -		.exit_latency		= 10,
>>>> +		.exit_latency		= 100,
>>>>    		.power_usage		= 50,
>>>> -		.target_residency	= 100,
>>>> +		.target_residency	= 1000,
>>>>    		.name			= "MV CPU IDLE",
>>>>    		.desc			= "CPU power down",
>>>>    	},
>>>>    	.states[2]		= {
>>>>    		.enter			= mvebu_v7_enter_idle,
>>>> -		.exit_latency		= 100,
>>>> +		.exit_latency		= 1000,
>>>>    		.power_usage		= 5,
>>>> -		.target_residency	= 1000,
>>>> +		.target_residency	= 10000,
>>>>    		.flags			= MVEBU_V7_FLAG_DEEP_IDLE,
>>>>    		.name			= "MV CPU DEEP IDLE",
>>>>    		.desc			= "CPU and L2 Fabric power down",
>>>
>>>
>>>
>>
>>
>> --
>> <http://www.linaro.org/> Linaro.org ? Open source software for ARM SoCs
>>
>> Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
>> <http://twitter.com/#!/linaroorg> Twitter |
>> <http://www.linaro.org/linaro-blog/> Blog
>
>


-- 
  <http://www.linaro.org/> Linaro.org ? Open source software for ARM SoCs

Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog

[PATCH] cpuidle: mvebu: update cpuidle thresholds for Armada XP SOCs

[Daniel Lezcano]

On 03/10/2015 07:05 PM, Thomas Petazzoni wrote:
> Hello Daniel,
>
> I know you suggested a more rigorous method of determining the exit
> latency and target residency times, but would it be nonetheless
> possible to apply this patch, which clearly improves performance a lot,
> and actually makes the code match the values used in the vendor kernel?
>
> I also think this patch should be marked for stable, it fixes values
> introduced in commit b858fbc1919720f7f54360098ece03b383e961fa, and
> should therefore be backported all the way to v3.16.

I applied the patch for v4.1.

I will let you send later an mail to stable@ with the commit-id to ask 
backport. I don't want to put a stable@ tag in the patch as it does not 
enter in the stable kernel rules.

Thanks
   -- Daniel



> On Fri, 13 Feb 2015 15:55:03 +0100 (CET), s. rannou wrote:
>> Originally, the thresholds used in the cpuidle driver for Armada SOCs
>> were temporarily chosen, leaving room for improvements.
>>
>> This commit updates the thresholds for the Armada XP SOCs with values
>> that positively impact performances:
>>
>>                                  without patch  with patch   vendor kernel
>>   - iperf localhost (gbit/sec)   ~3.7           ~6.4         ~5.4
>>   - ioping tmpfs (iops)          ~163k          ~206k        ~179k
>>   - ioping tmpfs (mib/s)         ~636           ~805         ~699
>>
>> The idle power consumption is negatively impacted (proportionally less
>> than the performance gain), and we are still performing better than
>> the vendor kernel here:
>>
>>                                  without patch   with patch  vendor kernel
>>   - power consumption idle (W)   ~2.4            ~3.2        ~4.4
>>   - power consumption busy (W)   ~8.6            ~8.3        ~8.6
>>
>> There is still room for improvement regarding the value of these
>> thresholds, they were chosen to mimic the vendor kernel.
>>
>> This patch only impacts Armada XP SOCs and was tested on Online Labs
>> C1 boards. A similar approach can be taken to improve the performances
>> of the Armada 370 and Armada 38x SOCs.
>>
>> Thanks a lot to Thomas Petazzoni, Gregory Clement and Willy Tarreau
>> for the discussions and tips around this topic.
>>
>> Signed-off-by: Sebastien Rannou <mxs@sbrk.org>
>> ---
>>   drivers/cpuidle/cpuidle-mvebu-v7.c | 8 ++++----
>>   1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/cpuidle/cpuidle-mvebu-v7.c b/drivers/cpuidle/cpuidle-mvebu-v7.c
>> index 38e6861..3716a1f 100644
>> --- a/drivers/cpuidle/cpuidle-mvebu-v7.c
>> +++ b/drivers/cpuidle/cpuidle-mvebu-v7.c
>> @@ -50,17 +50,17 @@ static struct cpuidle_driver armadaxp_idle_driver = {
>>   	.states[0]		= ARM_CPUIDLE_WFI_STATE,
>>   	.states[1]		= {
>>   		.enter			= mvebu_v7_enter_idle,
>> -		.exit_latency		= 10,
>> +		.exit_latency		= 100,
>>   		.power_usage		= 50,
>> -		.target_residency	= 100,
>> +		.target_residency	= 1000,
>>   		.name			= "MV CPU IDLE",
>>   		.desc			= "CPU power down",
>>   	},
>>   	.states[2]		= {
>>   		.enter			= mvebu_v7_enter_idle,
>> -		.exit_latency		= 100,
>> +		.exit_latency		= 1000,
>>   		.power_usage		= 5,
>> -		.target_residency	= 1000,
>> +		.target_residency	= 10000,
>>   		.flags			= MVEBU_V7_FLAG_DEEP_IDLE,
>>   		.name			= "MV CPU DEEP IDLE",
>>   		.desc			= "CPU and L2 Fabric power down",
>
>
>


-- 
  <http://www.linaro.org/> Linaro.org ? Open source software for ARM SoCs

Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
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