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| author | Christian Borntraeger <borntraeger@de.ibm.com> | 2019-02-15 13:47:20 +0100 |
|---|---|---|
| committer | Christian Borntraeger <borntraeger@de.ibm.com> | 2019-10-10 13:18:38 +0200 |
| commit | 8474e5cac07e7f21dd8c0b3620640db30115db56 (patch) | |
| tree | 41dabba55c3bacb5ca6c912765b87a6ae28f6327 /arch/s390/kvm/diag.c | |
| parent | efec8d219fb1bc2d7ab4f1c582e7beed44e309f4 (diff) | |
| download | linux-8474e5cac07e7f21dd8c0b3620640db30115db56.tar.bz2 | |
KVM: s390: count invalid yields
To analyze some performance issues with lock contention and scheduling
it is nice to know when diag9c did not result in any action or when
no action was tried.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Diffstat (limited to 'arch/s390/kvm/diag.c')
| -rw-r--r-- | arch/s390/kvm/diag.c | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c index 45634b3d2e0a..609c55df3ce8 100644 --- a/arch/s390/kvm/diag.c +++ b/arch/s390/kvm/diag.c @@ -158,14 +158,24 @@ static int __diag_time_slice_end_directed(struct kvm_vcpu *vcpu) tid = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4]; vcpu->stat.diagnose_9c++; - VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d", tid); + /* yield to self */ if (tid == vcpu->vcpu_id) - return 0; + goto no_yield; + /* yield to invalid */ tcpu = kvm_get_vcpu_by_id(vcpu->kvm, tid); - if (tcpu) - kvm_vcpu_yield_to(tcpu); + if (!tcpu) + goto no_yield; + + if (kvm_vcpu_yield_to(tcpu) <= 0) + goto no_yield; + + VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: done", tid); + return 0; +no_yield: + VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: ignored", tid); + vcpu->stat.diagnose_9c_ignored++; return 0; } |