The following commit has been merged into the sched/core branch of tip:
Commit-ID: 24f3cb558f59debe0e9159459bb9627b51b47c17
Gitweb: https://git.kernel.org/tip/24f3cb558f59debe0e9159459bb9627b51b47c17
Author: Johannes Weiner <hannes@xxxxxxxxxxx>
AuthorDate: Wed, 03 Mar 2021 11:46:58 +08:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Thu, 04 Mar 2021 09:56:02 +01:00
psi: Pressure states are unlikely
Move the unlikely branches out of line. This eliminates undesirable
jumps during wakeup and sleeps for workloads that aren't under any
sort of resource pressure.
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20210303034659.91735-4-zhouchengming@xxxxxxxxxxxxx
---
kernel/sched/psi.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 0fe6ff6..3907a6b 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -219,17 +219,17 @@ static bool test_state(unsigned int *tasks, enum psi_states state)
{
switch (state) {
case PSI_IO_SOME:
- return tasks[NR_IOWAIT];
+ return unlikely(tasks[NR_IOWAIT]);
case PSI_IO_FULL:
- return tasks[NR_IOWAIT] && !tasks[NR_RUNNING];
+ return unlikely(tasks[NR_IOWAIT] && !tasks[NR_RUNNING]);
case PSI_MEM_SOME:
- return tasks[NR_MEMSTALL];
+ return unlikely(tasks[NR_MEMSTALL]);
case PSI_MEM_FULL:
- return tasks[NR_MEMSTALL] && !tasks[NR_RUNNING];
+ return unlikely(tasks[NR_MEMSTALL] && !tasks[NR_RUNNING]);
case PSI_CPU_SOME:
- return tasks[NR_RUNNING] > tasks[NR_ONCPU];
+ return unlikely(tasks[NR_RUNNING] > tasks[NR_ONCPU]);
case PSI_CPU_FULL:
- return tasks[NR_RUNNING] && !tasks[NR_ONCPU];
+ return unlikely(tasks[NR_RUNNING] && !tasks[NR_ONCPU]);
case PSI_NONIDLE:
return tasks[NR_IOWAIT] || tasks[NR_MEMSTALL] ||
tasks[NR_RUNNING];
@@ -729,7 +729,7 @@ static void psi_group_change(struct psi_group *group, int cpu,
* task in a cgroup is in_memstall, the corresponding groupc
* on that cpu is in PSI_MEM_FULL state.
*/
- if (groupc->tasks[NR_ONCPU] && cpu_curr(cpu)->in_memstall)
+ if (unlikely(groupc->tasks[NR_ONCPU] && cpu_curr(cpu)->in_memstall))
state_mask |= (1 << PSI_MEM_FULL);
groupc->state_mask = state_mask;
|