Displaying 3 results from an estimated 3 matches for "rwsem_owner_is_writer".
2017 Feb 08
0
[PATCH 2/2] locking/mutex, rwsem: Reduce vcpu_is_preempted() calling frequency
...nel/locking/rwsem-xadd.c
+++ b/kernel/locking/rwsem-xadd.c
@@ -351,6 +351,7 @@ static inline bool rwsem_can_spin_on_owner(struct rw_semaphore *sem)
static noinline bool rwsem_spin_on_owner(struct rw_semaphore *sem)
{
struct task_struct *owner = READ_ONCE(sem->owner);
+ int loop = 0;
if (!rwsem_owner_is_writer(owner))
goto out;
@@ -367,10 +368,11 @@ static noinline bool rwsem_spin_on_owner(struct rw_semaphore *sem)
/*
* abort spinning when need_resched or owner is not running or
- * owner's cpu is preempted.
+ * owner's cpu is preempted. The preemption check is done at
+ * a low...
2017 Feb 08
4
[PATCH 1/2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function
It was found when running fio sequential write test with a XFS ramdisk
on a 2-socket x86-64 system, the %CPU times as reported by perf were
as follows:
71.27% 0.28% fio [k] down_write
70.99% 0.01% fio [k] call_rwsem_down_write_failed
69.43% 1.18% fio [k] rwsem_down_write_failed
65.51% 54.57% fio [k] osq_lock
9.72% 7.99% fio [k] __raw_callee_save___kvm_vcpu_is_preempted
4.16%
2017 Feb 08
4
[PATCH 1/2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function
It was found when running fio sequential write test with a XFS ramdisk
on a 2-socket x86-64 system, the %CPU times as reported by perf were
as follows:
71.27% 0.28% fio [k] down_write
70.99% 0.01% fio [k] call_rwsem_down_write_failed
69.43% 1.18% fio [k] rwsem_down_write_failed
65.51% 54.57% fio [k] osq_lock
9.72% 7.99% fio [k] __raw_callee_save___kvm_vcpu_is_preempted
4.16%