Dear Sarbojit,

Agreed with your point, thanks for raising it..

There was one issue in the total no of interrupt count in the previous chart preparation, actually the total no of interrupt is equal to the interrupt sent to Idle core.

On an average we are saving more than 25% of the IPIs sent to big domain CPUs. I just updated the below mentioned chart with the related data.

Case 1:

Video Recording – IPI reduced by 23.5%

Case 2:

Browsing and Audio(Background) – IPI reduced by 33.11%

Case 3:

Subway Surfer game – IPI reduced by 23.80%

Thanks,

Rahul Khandelwal

From: Sarbojit Ganguly [mailto:ganguly.s@samsung.com]
Sent: 25 August 2015 17:47
To: Rahul Khandelwal (Rahul Khandelwal); Unixman Linuxboy; Jon Medhurst (Tixy); hiren.gajjar@samsung.com
Cc: khilman@linaro.org; Morten.Rasmussen@arm.com; vincent.guittot@linaro.org; Gaurav Jindal (Gaurav Jindal); linaro-kernel@lists.linaro.org; Sanjeev Yadav (Sanjeev Kumar Yadav); chris.redpath@arm.com; Patrick Bellasi; Alex.Shi@linaro.org; Sarbojit Ganguly; SHARAN ALLUR
Subject: Re: RE: [PATCH 1/1] HMP: Do not send IPI if core already waked up

Hello Rahul,

Thanks for the metrics. I think there is some problem with the numbers. After we rule out 196 counts of IPI, the total IPI count should also get modified, isn't it?

Regards,

Sarbojit

------- Original Message -------

Sender : Rahul Khandelwal (Rahul Khandelwal)<Rahul.Khandelwal@spreadtrum.com>

Date : Aug 25, 2015 17:23 (GMT+05:30)

Title : RE: [PATCH 1/1] HMP: Do not send IPI if core already waked up

Dear All,

On an average we are saving around 25% of the IPIs sent to big domain CPUs. Following are the performance analysis in different cases :

Case 1:

Video Recording – IPI reduced by 23.5%

IPI reduced by 23.5 %

Case 2:

Browsing and Audio(Background) – IPI reduced by 33.11%

IPI reduced by 33.11 %

Case 3:

Subway Surfer game – IPI reduced by 23.80%

Thanks,

Rahul Khandelwal

From: Unixman Linuxboy [mailto:unixman.linuxboy@gmail.com]
Sent: 24 August 2015 18:23
To: Jon Medhurst (Tixy)
Cc: khilman@linaro.org; Morten.Rasmussen@arm.com; vincent.guittot@linaro.org; Gaurav Jindal (Gaurav Jindal); linaro-kernel@lists.linaro.org; Rahul Khandelwal (Rahul Khandelwal); Sanjeev Yadav (Sanjeev Kumar Yadav); chris.redpath@arm.com; Patrick Bellasi; Alex.Shi@linaro.org; ganguly.s@samsung.com; sharan.allur@samsung.com
Subject: Re: [PATCH 1/1] HMP: Do not send IPI if core already waked up

On 19 Aug 2015 17:58, "Jon Medhurst (Tixy)" <tixy@linaro.org> wrote:
>
> Adding Patrick Bellasi to the 'to' list as he's been working on HMP with
> Chris Redpath....
>
>
> On Wed, 2015-08-19 at 05:18 +0000, Rahul Khandelwal (Rahul Khandelwal) wrote:
>
> Dear All,
>
> Please consider the patch, It is related to HMP force up migration. It will avoid sending of unnecessary interrupts to CPUs of faster domain hence increase performance.
>
> --------------------------------------------------------------------------------------------------
> From 2d48749ac30a2c0a2ef77132f303d69605c3dd3f Mon Sep 17 00:00:00 2001
> From: rahulkhandelwal <rahul.khandelwal@spreadtrum.com>
> Date: Fri, 14 Aug 2015 16:36:17 +0800
> Subject: [PATCH 1/1] HMP: Do not send IPI if core already waked up
>
> It is possible that we are sending IPI to a cpu in faster domain which is
> already waked up by other CPU in smaller domain.
>
> HMP select the idle CPU using hmp_domain_min_load. Based on that HMP send IPI
> to the idle cpu in faster domain. There could be some latency by the core to
> wake up and set wake_for_idle_pull = 0. Next smaller cpu again check for
> idle CPU in faster domain and send IPI to already waked up CPU.
>
> For example: In Octacore system, 0-3 are slower CPUs and 4-7 are faster CPUs.
> CPU0 and CPU1 has heavy tasks and CPU4 is idle.
> CPU0 execute hmp_force_up_migration find CPU4 as idle, it send IPI to CPU4
> and return. After that CPU1 got the chance to run hmp_force_up_migration,
> it again find CPU4 as idle, send IPI to CPU4, which is not required.
>
> Signed-off-by: rahulkhandelwal <rahul.khandelwal@spreadtrum.com>
> ---
> kernel/sched/fair.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 1baf641..388836c 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -7200,6 +7200,11 @@ static void hmp_force_up_migration(int this_cpu)
> }
> p = task_of(curr);
> if (hmp_up_migration(cpu, &target_cpu, curr)) {
> + if (cpu_rq(target_cpu)->wake_for_idle_pull == 1) {
> + raw_spin_unlock_irqrestore(&target->lock, flags);
> + spin_unlock(&hmp_force_migration);
> + return;
> + }
> cpu_rq(target_cpu)->wake_for_idle_pull = 1;
> raw_spin_unlock_irqrestore(&target->lock, flags);
> spin_unlock(&hmp_force_migration);

Can you please share the actual performance numbers gained by this patch?

> --
> 1.7.9.5
>
>
>
>
> _______________________________________________
> linaro-kernel mailing list
> linaro-kernel@lists.linaro.org
> https://lists.linaro.org/mailman/listinfo/linaro-kernel

감사합니다

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