All of lore.kernel.org
 help / color / mirror / Atom feed
From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Lingutla Chandrasekhar <clingutla@codeaurora.org>,
	quentin.perret@arm.com, sudeep.holla@arm.com,
	gregkh@linuxfoundation.org
Cc: will.deacon@arm.com, catalin.marinas@arm.com,
	morten.rasmussen@arm.com, linux-arm-kernel@lists.infradead.org,
	jeremy.linton@arm.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1] arch_topology: Make cpu_capacity sysfs node as ready-only
Date: Fri, 8 Mar 2019 12:45:11 +0100	[thread overview]
Message-ID: <df8c3952-b1ab-bc15-ccb7-e4a5d7d54bf8@arm.com> (raw)
In-Reply-To: <1551886073-16217-1-git-send-email-clingutla@codeaurora.org>

On 3/6/19 4:27 PM, Lingutla Chandrasekhar wrote:

[...]

> @@ -51,37 +50,7 @@ static ssize_t cpu_capacity_show(struct device *dev,
>   static void update_topology_flags_workfn(struct work_struct *work);
>   static DECLARE_WORK(update_topology_flags_work, update_topology_flags_workfn);
>   
> -static ssize_t cpu_capacity_store(struct device *dev,
> -				  struct device_attribute *attr,
> -				  const char *buf,
> -				  size_t count)
> -{
> -	struct cpu *cpu = container_of(dev, struct cpu, dev);
> -	int this_cpu = cpu->dev.id;
> -	int i;
> -	unsigned long new_capacity;
> -	ssize_t ret;
> -
> -	if (!count)
> -		return 0;
> -
> -	ret = kstrtoul(buf, 0, &new_capacity);
> -	if (ret)
> -		return ret;
> -	if (new_capacity > SCHED_CAPACITY_SCALE)
> -		return -EINVAL;
> -
> -	mutex_lock(&cpu_scale_mutex);

Since we can't write to cpu_scale from here anymore, we could get rid of 
cpu_scale_mutex. 
topology_normalize_cpu_scale()->topology_set_cpu_scale() is now only 
called from:

[    0.202628]  topology_normalize_cpu_scale+0x28/0x30
[    0.207529]  init_cpu_topology+0x168/0x1e8
[    0.211644]  smp_prepare_cpus+0x2c/0x108
[    0.215585]  kernel_init_freeable+0x104/0x518
[    0.219963]  kernel_init+0x18/0x110
[    0.223469]  ret_from_fork+0x10/0x1c

for dts capacity-dmips-mhz properties

and

[    3.130180]  topology_normalize_cpu_scale.part.0+0xac/0xd0
[    3.135619]  init_cpu_capacity_callback+0x100/0x178
[    3.140459]  notifier_call_chain+0x5c/0xa0
[    3.144522]  blocking_notifier_call_chain+0x64/0x88
[    3.149363]  cpufreq_set_policy+0xd8/0x3c8
[    3.153427]  cpufreq_init_policy+0x78/0xc8

for cpufreq max frequency related adjustments to cpu capacity.

The mutex was introduced for the sysfs interface here: 
https://lore.kernel.org/lkml/1468932048-31635-8-git-send-email-juri.lelli@arm.com

> -	for_each_cpu(i, &cpu_topology[this_cpu].core_sibling)
> -		topology_set_cpu_scale(i, new_capacity);
> -	mutex_unlock(&cpu_scale_mutex);
> -
> -	schedule_work(&update_topology_flags_work);
> -
> -	return count;
> -}
> -
> -static DEVICE_ATTR_RW(cpu_capacity);
> +static DEVICE_ATTR_RO(cpu_capacity);
>   
>   static int register_cpu_capacity_sysctl(void)
>   {
> 

Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>

on Arm64 Juno with v5.0

WARNING: multiple messages have this Message-ID (diff)
From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Lingutla Chandrasekhar <clingutla@codeaurora.org>,
	quentin.perret@arm.com, sudeep.holla@arm.com,
	gregkh@linuxfoundation.org
Cc: catalin.marinas@arm.com, will.deacon@arm.com,
	linux-kernel@vger.kernel.org, jeremy.linton@arm.com,
	morten.rasmussen@arm.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v1] arch_topology: Make cpu_capacity sysfs node as ready-only
Date: Fri, 8 Mar 2019 12:45:11 +0100	[thread overview]
Message-ID: <df8c3952-b1ab-bc15-ccb7-e4a5d7d54bf8@arm.com> (raw)
In-Reply-To: <1551886073-16217-1-git-send-email-clingutla@codeaurora.org>

On 3/6/19 4:27 PM, Lingutla Chandrasekhar wrote:

[...]

> @@ -51,37 +50,7 @@ static ssize_t cpu_capacity_show(struct device *dev,
>   static void update_topology_flags_workfn(struct work_struct *work);
>   static DECLARE_WORK(update_topology_flags_work, update_topology_flags_workfn);
>   
> -static ssize_t cpu_capacity_store(struct device *dev,
> -				  struct device_attribute *attr,
> -				  const char *buf,
> -				  size_t count)
> -{
> -	struct cpu *cpu = container_of(dev, struct cpu, dev);
> -	int this_cpu = cpu->dev.id;
> -	int i;
> -	unsigned long new_capacity;
> -	ssize_t ret;
> -
> -	if (!count)
> -		return 0;
> -
> -	ret = kstrtoul(buf, 0, &new_capacity);
> -	if (ret)
> -		return ret;
> -	if (new_capacity > SCHED_CAPACITY_SCALE)
> -		return -EINVAL;
> -
> -	mutex_lock(&cpu_scale_mutex);

Since we can't write to cpu_scale from here anymore, we could get rid of 
cpu_scale_mutex. 
topology_normalize_cpu_scale()->topology_set_cpu_scale() is now only 
called from:

[    0.202628]  topology_normalize_cpu_scale+0x28/0x30
[    0.207529]  init_cpu_topology+0x168/0x1e8
[    0.211644]  smp_prepare_cpus+0x2c/0x108
[    0.215585]  kernel_init_freeable+0x104/0x518
[    0.219963]  kernel_init+0x18/0x110
[    0.223469]  ret_from_fork+0x10/0x1c

for dts capacity-dmips-mhz properties

and

[    3.130180]  topology_normalize_cpu_scale.part.0+0xac/0xd0
[    3.135619]  init_cpu_capacity_callback+0x100/0x178
[    3.140459]  notifier_call_chain+0x5c/0xa0
[    3.144522]  blocking_notifier_call_chain+0x64/0x88
[    3.149363]  cpufreq_set_policy+0xd8/0x3c8
[    3.153427]  cpufreq_init_policy+0x78/0xc8

for cpufreq max frequency related adjustments to cpu capacity.

The mutex was introduced for the sysfs interface here: 
https://lore.kernel.org/lkml/1468932048-31635-8-git-send-email-juri.lelli@arm.com

> -	for_each_cpu(i, &cpu_topology[this_cpu].core_sibling)
> -		topology_set_cpu_scale(i, new_capacity);
> -	mutex_unlock(&cpu_scale_mutex);
> -
> -	schedule_work(&update_topology_flags_work);
> -
> -	return count;
> -}
> -
> -static DEVICE_ATTR_RW(cpu_capacity);
> +static DEVICE_ATTR_RO(cpu_capacity);
>   
>   static int register_cpu_capacity_sysctl(void)
>   {
> 

Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>

on Arm64 Juno with v5.0

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2019-03-08 11:45 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-28 11:53 [PATCH] arch_topology: Update user supplied capacity to possible cpus in cluster Lingutla Chandrasekhar
2019-02-28 12:19 ` Sudeep Holla
2019-02-28 14:38   ` Chandra Sekhar Lingutla
2019-02-28 15:25     ` Sudeep Holla
2019-03-02 13:30       ` Chandra Sekhar Lingutla
2019-03-04 18:21         ` Sudeep Holla
2019-03-05  9:23           ` Quentin Perret
2019-03-05 11:13             ` Sudeep Holla
2019-03-05 11:29               ` Quentin Perret
2019-03-05 11:36                 ` Sudeep Holla
2019-03-05 15:53                   ` Chandra Sekhar Lingutla
2019-03-05 16:12                     ` Quentin Perret
2019-03-05 16:54                     ` Sudeep Holla
2019-03-06 15:22                       ` Morten Rasmussen
2019-03-06 15:27                         ` [PATCH v1] arch_topology: Make cpu_capacity sysfs node as ready-only Lingutla Chandrasekhar
2019-03-06 15:27                           ` Lingutla Chandrasekhar
2019-03-07  7:28                           ` Juri Lelli
2019-03-07  7:28                             ` Juri Lelli
2019-03-07  9:31                             ` Quentin Perret
2019-03-07  9:31                               ` Quentin Perret
2019-03-07  9:57                               ` Juri Lelli
2019-03-07  9:57                                 ` Juri Lelli
2019-03-07 12:14                                 ` Quentin Perret
2019-03-07 12:14                                   ` Quentin Perret
2019-03-07 15:04                                   ` Sudeep Holla
2019-03-07 15:04                                     ` Sudeep Holla
2019-03-07 15:19                           ` Sudeep Holla
2019-03-07 15:19                             ` Sudeep Holla
2019-03-08 11:45                           ` Dietmar Eggemann [this message]
2019-03-08 11:45                             ` Dietmar Eggemann
2019-03-08 12:38                             ` [PATCH v2] " Lingutla Chandrasekhar
2019-03-08 12:38                               ` Lingutla Chandrasekhar
2019-03-27 10:56                               ` Quentin Perret
2019-03-27 10:56                                 ` Quentin Perret
2019-03-06  9:48                 ` [PATCH] arch_topology: Update user supplied capacity to possible cpus in cluster Dietmar Eggemann

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=df8c3952-b1ab-bc15-ccb7-e4a5d7d54bf8@arm.com \
    --to=dietmar.eggemann@arm.com \
    --cc=catalin.marinas@arm.com \
    --cc=clingutla@codeaurora.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=jeremy.linton@arm.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=morten.rasmussen@arm.com \
    --cc=quentin.perret@arm.com \
    --cc=sudeep.holla@arm.com \
    --cc=will.deacon@arm.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.