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cpuset: Use descriptive text when reading/writing cpuset.sched.partition 

Currently, cpuset.sched.partition returns the values, 0, 1 or -1 on
read. A person who is not familiar with the partition code may not
understand what they mean.

In order to make cpuset.sched.partition more user-friendly, it will
now display the following descriptive text on read:

  "root" - A partition root (top cpuset of a partition)
  "member" - A non-root member of a partition
  "root invalid" - An invalid partition root

Note that there is at least one partition in the whole cgroup hierarchy.
The top cpuset is the root of that partition.  The rests are either a
root if it starts a new partition or a member of a partition.

The cpuset.sched.partition file will now also accept "root" and
"member" besides 1 and 0 as valid input values. The "root invalid"
value is internal only and cannot be written to the file.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Waiman Long 2018-11-08 10:08:44 -05:00 committed by Tejun Heo
parent 5776ceccd4
commit bb5b553c33
1 changed files with 51 additions and 7 deletions
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58
kernel/cgroup/cpuset.c
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@ -2278,9 +2278,6 @@ static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft,
case FILE_SCHED_RELAX_DOMAIN_LEVEL:
retval = update_relax_domain_level(cs, val);
break;
case FILE_PARTITION_ROOT:
retval = update_prstate(cs, val);
break;
default:
retval = -EINVAL;
break;
@ -2431,8 +2428,6 @@ static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)
switch (type) {
case FILE_SCHED_RELAX_DOMAIN_LEVEL:
return cs->relax_domain_level;
case FILE_PARTITION_ROOT:
return cs->partition_root_state;
default:
BUG();
}
@ -2441,6 +2436,55 @@ static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)
return 0;
}
static int sched_partition_show(struct seq_file *seq, void *v)
{
struct cpuset *cs = css_cs(seq_css(seq));
switch (cs->partition_root_state) {
case PRS_ENABLED:
seq_puts(seq, "root\n");
break;
case PRS_DISABLED:
seq_puts(seq, "member\n");
break;
case PRS_ERROR:
seq_puts(seq, "root invalid\n");
break;
}
return 0;
}
static ssize_t sched_partition_write(struct kernfs_open_file *of, char *buf,
size_t nbytes, loff_t off)
{
struct cpuset *cs = css_cs(of_css(of));
int val;
int retval = -ENODEV;
buf = strstrip(buf);
/*
* Convert "root"/"1" to 1, and convert "member"/"0" to 0.
*/
if (!strcmp(buf, "root") || !strcmp(buf, "1"))
val = PRS_ENABLED;
else if (!strcmp(buf, "member") || !strcmp(buf, "0"))
val = PRS_DISABLED;
else
return -EINVAL;
css_get(&cs->css);
mutex_lock(&cpuset_mutex);
if (!is_cpuset_online(cs))
goto out_unlock;
retval = update_prstate(cs, val);
out_unlock:
mutex_unlock(&cpuset_mutex);
css_put(&cs->css);
return retval ?: nbytes;
}
/*
* for the common functions, 'private' gives the type of file
*/
@ -2584,8 +2628,8 @@ static struct cftype dfl_files[] = {
{
.name = "sched.partition",
.read_s64 = cpuset_read_s64,
.write_s64 = cpuset_write_s64,
.seq_show = sched_partition_show,
.write = sched_partition_write,
.private = FILE_PARTITION_ROOT,
.flags = CFTYPE_NOT_ON_ROOT,
},