[PATCH -next] cgroup/misc: Introduce misc.peak

[PATCH -next] cgroup/misc: Introduce misc.peak

[Xiu Jianfeng]

Introduce misc.peak to record the historical maximum usage of the
resource, as in some scenarios the value of misc.max could be
adjusted based on the peak usage of the resource.

Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
---
 Documentation/admin-guide/cgroup-v2.rst |  9 ++++++++
 include/linux/misc_cgroup.h             |  2 ++
 kernel/cgroup/misc.c                    | 29 +++++++++++++++++++++++++
 3 files changed, 40 insertions(+)

diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index ae0fdb6fc618..48ae30f2d9ab 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -2646,6 +2646,15 @@ Miscellaneous controller provides 3 interface files. If two misc resources (res_
 	  res_a 3
 	  res_b 0
 
+  misc.peak
+        A read-only flat-keyed file shown in the all cgroups.  It shows
+        the historical maximum usage of the resources in the cgroup and
+        its children.::
+
+	  $ cat misc.peak
+	  res_a 10
+	  res_b 8
+
   misc.max
         A read-write flat-keyed file shown in the non root cgroups. Allowed
         maximum usage of the resources in the cgroup and its children.::
diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h
index e799b1f8d05b..8aa69818291e 100644
--- a/include/linux/misc_cgroup.h
+++ b/include/linux/misc_cgroup.h
@@ -30,11 +30,13 @@ struct misc_cg;
 /**
  * struct misc_res: Per cgroup per misc type resource
  * @max: Maximum limit on the resource.
+ * $watermark: Historical maximum usage of the resource.
  * @usage: Current usage of the resource.
  * @events: Number of times, the resource limit exceeded.
  */
 struct misc_res {
 	u64 max;
+	u64 watermark;
 	atomic64_t usage;
 	atomic64_t events;
 };
diff --git a/kernel/cgroup/misc.c b/kernel/cgroup/misc.c
index 79a3717a5803..a1b6ed76e00b 100644
--- a/kernel/cgroup/misc.c
+++ b/kernel/cgroup/misc.c
@@ -159,6 +159,8 @@ int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg, u64 amount)
 			ret = -EBUSY;
 			goto err_charge;
 		}
+		if (new_usage > READ_ONCE(res->watermark))
+			WRITE_ONCE(res->watermark, new_usage);
 	}
 	return 0;
 
@@ -307,6 +309,29 @@ static int misc_cg_current_show(struct seq_file *sf, void *v)
 	return 0;
 }
 
+/**
+ * misc_cg_peak_show() - Show the peak usage of the misc cgroup.
+ * @sf: Interface file
+ * @v: Arguments passed
+ *
+ * Context: Any context.
+ * Return: 0 to denote successful print.
+ */
+static int misc_cg_peak_show(struct seq_file *sf, void *v)
+{
+	int i;
+	u64 watermark;
+	struct misc_cg *cg = css_misc(seq_css(sf));
+
+	for (i = 0; i < MISC_CG_RES_TYPES; i++) {
+		watermark = READ_ONCE(cg->res[i].watermark);
+		if (READ_ONCE(misc_res_capacity[i]) || watermark)
+			seq_printf(sf, "%s %llu\n", misc_res_name[i], watermark);
+	}
+
+	return 0;
+}
+
 /**
  * misc_cg_capacity_show() - Show the total capacity of misc res on the host.
  * @sf: Interface file
@@ -357,6 +382,10 @@ static struct cftype misc_cg_files[] = {
 		.name = "current",
 		.seq_show = misc_cg_current_show,
 	},
+	{
+		.name = "peak",
+		.seq_show = misc_cg_peak_show,
+	},
 	{
 		.name = "capacity",
 		.seq_show = misc_cg_capacity_show,
-- 
2.34.1

Re: [PATCH -next] cgroup/misc: Introduce misc.peak

[Randy Dunlap]

Hi--

On 7/1/24 5:52 AM, Xiu Jianfeng wrote:
> Introduce misc.peak to record the historical maximum usage of the
> resource, as in some scenarios the value of misc.max could be
> adjusted based on the peak usage of the resource.
> 
> Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
> ---
>  Documentation/admin-guide/cgroup-v2.rst |  9 ++++++++
>  include/linux/misc_cgroup.h             |  2 ++
>  kernel/cgroup/misc.c                    | 29 +++++++++++++++++++++++++
>  3 files changed, 40 insertions(+)
> 
> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
> index ae0fdb6fc618..48ae30f2d9ab 100644
> --- a/Documentation/admin-guide/cgroup-v2.rst
> +++ b/Documentation/admin-guide/cgroup-v2.rst
> @@ -2646,6 +2646,15 @@ Miscellaneous controller provides 3 interface files. If two misc resources (res_
>  	  res_a 3
>  	  res_b 0
>  
> +  misc.peak
> +        A read-only flat-keyed file shown in the all cgroups.  It shows

	                               shown in all cgroups. It shows

> +        the historical maximum usage of the resources in the cgroup and
> +        its children.::
> +
> +	  $ cat misc.peak
> +	  res_a 10
> +	  res_b 8
> +
>    misc.max
>          A read-write flat-keyed file shown in the non root cgroups. Allowed
>          maximum usage of the resources in the cgroup and its children.::
> diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h
> index e799b1f8d05b..8aa69818291e 100644
> --- a/include/linux/misc_cgroup.h
> +++ b/include/linux/misc_cgroup.h
> @@ -30,11 +30,13 @@ struct misc_cg;
>  /**
>   * struct misc_res: Per cgroup per misc type resource
>   * @max: Maximum limit on the resource.
> + * $watermark: Historical maximum usage of the resource.

      @watermark:

>   * @usage: Current usage of the resource.
>   * @events: Number of times, the resource limit exceeded.
>   */
>  struct misc_res {
>  	u64 max;
> +	u64 watermark;
>  	atomic64_t usage;
>  	atomic64_t events;
>  };


-- 
~Randy

Re: [PATCH -next] cgroup/misc: Introduce misc.peak

[Tejun Heo]

On Mon, Jul 01, 2024 at 12:52:59PM +0000, Xiu Jianfeng wrote:
> +		if (new_usage > READ_ONCE(res->watermark))
> +			WRITE_ONCE(res->watermark, new_usage);

It'd be better to do cmpxchg loop on update. That doesn't make it noticeably
more expensive and the peak tracking would actually be accurate.

Thanks.

-- 
tejun

Re: [PATCH -next] cgroup/misc: Introduce misc.peak

[xiujianfeng]

On 2024/7/1 23:01, Randy Dunlap wrote:
> Hi--
> 
> On 7/1/24 5:52 AM, Xiu Jianfeng wrote:
>> Introduce misc.peak to record the historical maximum usage of the
>> resource, as in some scenarios the value of misc.max could be
>> adjusted based on the peak usage of the resource.
>>
>> Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
>> ---
>>  Documentation/admin-guide/cgroup-v2.rst |  9 ++++++++
>>  include/linux/misc_cgroup.h             |  2 ++
>>  kernel/cgroup/misc.c                    | 29 +++++++++++++++++++++++++
>>  3 files changed, 40 insertions(+)
>>
>> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
>> index ae0fdb6fc618..48ae30f2d9ab 100644
>> --- a/Documentation/admin-guide/cgroup-v2.rst
>> +++ b/Documentation/admin-guide/cgroup-v2.rst
>> @@ -2646,6 +2646,15 @@ Miscellaneous controller provides 3 interface files. If two misc resources (res_
>>  	  res_a 3
>>  	  res_b 0
>>  
>> +  misc.peak
>> +        A read-only flat-keyed file shown in the all cgroups.  It shows
> 
> 	                               shown in all cgroups. It shows

Thanks for your review, will fix it in v2.
> 
>> +        the historical maximum usage of the resources in the cgroup and
>> +        its children.::
>> +
>> +	  $ cat misc.peak
>> +	  res_a 10
>> +	  res_b 8
>> +
>>    misc.max
>>          A read-write flat-keyed file shown in the non root cgroups. Allowed
>>          maximum usage of the resources in the cgroup and its children.::
>> diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h
>> index e799b1f8d05b..8aa69818291e 100644
>> --- a/include/linux/misc_cgroup.h
>> +++ b/include/linux/misc_cgroup.h
>> @@ -30,11 +30,13 @@ struct misc_cg;
>>  /**
>>   * struct misc_res: Per cgroup per misc type resource
>>   * @max: Maximum limit on the resource.
>> + * $watermark: Historical maximum usage of the resource.
> 
>       @watermark:
> 
>>   * @usage: Current usage of the resource.
>>   * @events: Number of times, the resource limit exceeded.
>>   */
>>  struct misc_res {
>>  	u64 max;
>> +	u64 watermark;
>>  	atomic64_t usage;
>>  	atomic64_t events;
>>  };
> 
> 

Re: [PATCH -next] cgroup/misc: Introduce misc.peak

[xiujianfeng]

On 2024/7/2 1:19, Tejun Heo wrote:
> On Mon, Jul 01, 2024 at 12:52:59PM +0000, Xiu Jianfeng wrote:
>> +		if (new_usage > READ_ONCE(res->watermark))
>> +			WRITE_ONCE(res->watermark, new_usage);
> 
> It'd be better to do cmpxchg loop on update. That doesn't make it noticeably
> more expensive and the peak tracking would actually be accurate.

Thanks for your review, will do in v2.

> 
> Thanks.
>