Commit fddc8bab authored by Johannes Weiner's avatar Johannes Weiner Committed by Ingo Molnar
Browse files

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: default avatarJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarChengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210303034659.91735-4-zhouchengming@bytedance.com
parent 7fae6c81

kernel/sched/psi.c

+7 −7
Original line number Diff line number Diff line
@@ -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;