A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-29 19:21:31 -04:00
Code Issues Projects Releases Packages Wiki Activity

sched/smt: Make sched_smt_present track topology

Browse source 
Currently the 'sched_smt_present' static key is enabled when at CPU bringup
SMT topology is observed, but it is never disabled. However there is demand
to also disable the key when the topology changes such that there is no SMT
present anymore.

Implement this by making the key count the number of cores that have SMT
enabled.

In particular, the SMT topology bits are set before interrrupts are enabled
and similarly, are cleared after interrupts are disabled for the last time
and the CPU dies.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Ingo Molnar <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Jiri Kosina <[email protected]>
Cc: Tom Lendacky <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Tim Chen <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Casey Schaufler <[email protected]>
Cc: Asit Mallick <[email protected]>
Cc: Arjan van de Ven <[email protected]>
Cc: Jon Masters <[email protected]>
Cc: Waiman Long <[email protected]>
Cc: Greg KH <[email protected]>
Cc: Dave Stewart <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]
This commit is contained in:
Peter Zijlstra (Intel) 2018-11-25 19:33:36 +01:00 • committed by Thomas Gleixner
commit c5511d03ec
1 changed files with 11 additions and 8 deletions
Download patch file Download diff file Expand all files Collapse all files

19
kernel/sched/core.c
View file

@ -5738,15 +5738,10 @@ int sched_cpu_activate(unsigned int cpu)
#ifdef CONFIG_SCHED_SMT
/*
* The sched_smt_present static key needs to be evaluated on every
* hotplug event because at boot time SMT might be disabled when
* the number of booted CPUs is limited.
*
* If then later a sibling gets hotplugged, then the key would stay
* off and SMT scheduling would never be functional.
* When going up, increment the number of cores with SMT present.
*/
if (cpumask_weight(cpu_smt_mask(cpu)) > 1)
static_branch_enable_cpuslocked(&sched_smt_present);
if (cpumask_weight(cpu_smt_mask(cpu)) == 2)
static_branch_inc_cpuslocked(&sched_smt_present);
#endif
set_cpu_active(cpu, true);
@ -5790,6 +5785,14 @@ int sched_cpu_deactivate(unsigned int cpu)
*/
synchronize_rcu_mult(call_rcu, call_rcu_sched);
#ifdef CONFIG_SCHED_SMT
/*
* When going down, decrement the number of cores with SMT present.
*/
if (cpumask_weight(cpu_smt_mask(cpu)) == 2)
static_branch_dec_cpuslocked(&sched_smt_present);
#endif
if (!sched_smp_initialized)
return 0;