From: zhouchengming <zhouchengm...@bytedance.com>
When I run a simple "perf bench sched pipe" test in a cgroup on my
machine, the output of "watch -d -n 1 cpu.pressure" of this cgroup
will report some avg10 10%-20%.
It's strange because there is not any other process in the cgroup.
Then I found that cpu contention/wait percentage came from outside
of the cgroup and the cpu idle latency, not wait for threads in
the cgroup.
So I think adding PSI_CPU_FULL state will be useful for container
workloads to distinguish between outside cgroup resource contention
and inside cgroup resource contention.
What's more, the PSI_CPU_FULL state includes the latency of the cpu
idle itself, so we can see the system sum latency introduced by cpu
idle state.
Signed-off-by: zhouchengming <zhouchengm...@bytedance.com>
---
include/linux/psi_types.h | 3 ++-
kernel/sched/psi.c | 9 +++++++--
2 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/include/linux/psi_types.h b/include/linux/psi_types.h
index b95f3211566a..0a23300d49af 100644
--- a/include/linux/psi_types.h
+++ b/include/linux/psi_types.h
@@ -50,9 +50,10 @@ enum psi_states {
PSI_MEM_SOME,
PSI_MEM_FULL,
PSI_CPU_SOME,
+ PSI_CPU_FULL,
/* Only per-CPU, to weigh the CPU in the global average: */
PSI_NONIDLE,
- NR_PSI_STATES = 6,
+ NR_PSI_STATES = 7,
};
enum psi_aggregators {
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 967732c0766c..234047e368a5 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -224,7 +224,9 @@ static bool test_state(unsigned int *tasks, enum psi_states
state)
case PSI_MEM_FULL:
return tasks[NR_MEMSTALL] && !tasks[NR_RUNNING];
case PSI_CPU_SOME:
- return tasks[NR_RUNNING] > tasks[NR_ONCPU];
+ return tasks[NR_RUNNING] > tasks[NR_ONCPU] && tasks[NR_ONCPU];
+ case PSI_CPU_FULL:
+ return tasks[NR_RUNNING] && !tasks[NR_ONCPU];
case PSI_NONIDLE:
return tasks[NR_IOWAIT] || tasks[NR_MEMSTALL] ||
tasks[NR_RUNNING];
@@ -681,6 +683,9 @@ static void record_times(struct psi_group_cpu *groupc, int
cpu,
if (groupc->state_mask & (1 << PSI_CPU_SOME))
groupc->times[PSI_CPU_SOME] += delta;
+ if (groupc->state_mask & (1 << PSI_CPU_FULL))
+ groupc->times[PSI_CPU_FULL] += delta;
+
if (groupc->state_mask & (1 << PSI_NONIDLE))
groupc->times[PSI_NONIDLE] += delta;
}
@@ -1018,7 +1023,7 @@ int psi_show(struct seq_file *m, struct psi_group *group,
enum psi_res res)
group->avg_next_update = update_averages(group, now);
mutex_unlock(&group->avgs_lock);
- for (full = 0; full < 2 - (res == PSI_CPU); full++) {
+ for (full = 0; full < 2; full++) {
unsigned long avg[3];
u64 total;
int w;
--
2.11.0
