Commit 1028f391 authored by Xiu Jianfeng's avatar Xiu Jianfeng Committed by Tejun Heo
Browse files

cgroup/misc: Introduce misc.peak 



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: default avatarXiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 7a447968

Documentation/admin-guide/cgroup-v2.rst

+9 −0
Original line number Diff line number Diff line
@@ -2642,6 +2642,15 @@ 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 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.::

include/linux/misc_cgroup.h

+2 −0
Original line number Diff line number Diff line
@@ -31,11 +31,13 @@ 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;

	atomic64_t watermark;

	atomic64_t usage;

	atomic64_t events;

};

kernel/cgroup/misc.c

+41 −0
Original line number Diff line number Diff line
@@ -121,6 +121,19 @@ static void misc_cg_cancel_charge(enum misc_res_type type, struct misc_cg *cg, 
		  misc_res_name[type]);

}



static void misc_cg_update_watermark(struct misc_res *res, u64 new_usage)

{

	u64 old;



	while (true) {

		old = atomic64_read(&res->watermark);

		if (new_usage <= old)

			break;

		if (atomic64_cmpxchg(&res->watermark, old, new_usage) == old)

			break;

	}

}



/**

 * misc_cg_try_charge() - Try charging the misc cgroup.

 * @type: Misc res type to charge.
@@ -159,6 +172,7 @@ int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg, u64 amount) 
			ret = -EBUSY;

			goto err_charge;

		}

		misc_cg_update_watermark(res, new_usage);

	}

	return 0;
@@ -307,6 +321,29 @@ 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 = atomic64_read(&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 +394,10 @@ 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,