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cgroup/misc: Introduce misc.peak

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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>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Xiu Jianfeng 2024-07-03 00:36:46 +00:00 committed by Tejun Heo
parent 7a4479680d
commit 1028f391d5
3 changed files with 52 additions and 0 deletions
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9
Documentation/admin-guide/cgroup-v2.rst
View File

@ -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.::

2
include/linux/misc_cgroup.h
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@ -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;
};

41
kernel/cgroup/misc.c
View File

@ -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,