sched: add /proc/sys/kernel/sched_compat_yield
add /proc/sys/kernel/sched_compat_yield to make sys_sched_yield()
more agressive, by moving the yielding task to the last position
in the rbtree.
with sched_compat_yield=0:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
2539 mingo 20 0 1576 252 204 R 50 0.0 0:02.03 loop_yield
2541 mingo 20 0 1576 244 196 R 50 0.0 0:02.05 loop
with sched_compat_yield=1:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
2584 mingo 20 0 1576 248 196 R 99 0.0 0:52.45 loop
2582 mingo 20 0 1576 256 204 R 0 0.0 0:00.00 loop_yield
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 6ace893..53a456e 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -303,6 +303,14 @@
.proc_handler = &proc_dointvec,
},
#endif
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "sched_compat_yield",
+ .data = &sysctl_sched_compat_yield,
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
#ifdef CONFIG_PROVE_LOCKING
{
.ctl_name = CTL_UNNUMBERED,