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cgroup/rdma: add rdma.peak for per-device peak usage tracking

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rdma.peak tracks the high watermark of resource usage per device,
giving a better baseline on which to set rdma.max. Polling
rdma.current isn't feasible since it would miss short-lived spikes.

This interface is analogous to memory.peak.

Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tao Cui 2026-05-14 14:50:31 +08:00 committed by Tejun Heo
parent 2a7d34eba5
commit c68095c4a4
1 changed files with 40 additions and 0 deletions
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40
kernel/cgroup/rdma.c
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@ -44,6 +44,7 @@ static LIST_HEAD(rdmacg_devices);
enum rdmacg_file_type {
RDMACG_RESOURCE_TYPE_MAX,
RDMACG_RESOURCE_TYPE_STAT,
RDMACG_RESOURCE_TYPE_PEAK,
};
/*
@ -60,6 +61,7 @@ static char const *rdmacg_resource_names[] = {
struct rdmacg_resource {
int max;
int usage;
int peak;
};
/*
@ -204,6 +206,17 @@ uncharge_cg_locked(struct rdma_cgroup *cg,
rpool->usage_sum--;
if (rpool->usage_sum == 0 &&
rpool->num_max_cnt == RDMACG_RESOURCE_MAX) {
int i;
/*
* Keep the rpool alive if any peak value is non-zero,
* so that rdma.peak persists as a historical high-
* watermark even after all resources are freed.
*/
for (i = 0; i < RDMACG_RESOURCE_MAX; i++) {
if (rpool->resources[i].peak)
return;
}
/*
* No user of the rpool and all entries are set to max, so
* safe to delete this rpool.
@ -310,6 +323,12 @@ int rdmacg_try_charge(struct rdma_cgroup **rdmacg,
}
}
}
/* Update peak only after all charges succeed */
for (p = cg; p; p = parent_rdmacg(p)) {
rpool = find_cg_rpool_locked(p, device);
if (rpool && rpool->resources[index].usage > rpool->resources[index].peak)
rpool->resources[index].peak = rpool->resources[index].usage;
}
mutex_unlock(&rdmacg_mutex);
*rdmacg = cg;
@ -472,6 +491,12 @@ static ssize_t rdmacg_resource_set_max(struct kernfs_open_file *of,
if (rpool->usage_sum == 0 &&
rpool->num_max_cnt == RDMACG_RESOURCE_MAX) {
int i;
for (i = 0; i < RDMACG_RESOURCE_MAX; i++) {
if (rpool->resources[i].peak)
goto dev_err;
}
/*
* No user of the rpool and all entries are set to max, so
* safe to delete this rpool.
@ -506,6 +531,8 @@ static void print_rpool_values(struct seq_file *sf,
value = rpool->resources[i].max;
else
value = S32_MAX;
} else if (sf_type == RDMACG_RESOURCE_TYPE_PEAK) {
value = rpool ? rpool->resources[i].peak : 0;
} else {
if (rpool)
value = rpool->resources[i].usage;
@ -556,6 +583,12 @@ static struct cftype rdmacg_files[] = {
.private = RDMACG_RESOURCE_TYPE_STAT,
.flags = CFTYPE_NOT_ON_ROOT,
},
{
.name = "peak",
.seq_show = rdmacg_resource_read,
.private = RDMACG_RESOURCE_TYPE_PEAK,
.flags = CFTYPE_NOT_ON_ROOT,
},
{ } /* terminate */
};
@ -575,6 +608,13 @@ rdmacg_css_alloc(struct cgroup_subsys_state *parent)
static void rdmacg_css_free(struct cgroup_subsys_state *css)
{
struct rdma_cgroup *cg = css_rdmacg(css);
struct rdmacg_resource_pool *rpool, *tmp;
/* Clean up rpools kept alive by non-zero peak values */
mutex_lock(&rdmacg_mutex);
list_for_each_entry_safe(rpool, tmp, &cg->rpools, cg_node)
free_cg_rpool_locked(rpool);
mutex_unlock(&rdmacg_mutex);
kfree(cg);
}