On 04/24/2012 10:24 AM, Christian Borntraeger wrote:
> From: Konstantin Weitz <[email protected]>
>
> This patch implements the directed yield hypercall found on other
> System z hypervisors. It delegates execution time to the virtual cpu
> specified in the instruction's parameter.
>
> Useful to avoid long spinlock waits in the guest.
>
>
> diff --git a/arch/s390/include/asm/kvm_host.h
> b/arch/s390/include/asm/kvm_host.h
> index 7343872..dd17537 100644
> --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -148,6 +148,7 @@ struct kvm_vcpu_stat {
> u32 instruction_sigp_restart;
> u32 diagnose_10;
> u32 diagnose_44;
> + u32 diagnose_9c;
> };
>
> struct kvm_s390_io_info {
> diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c
> index a353f0e..8991009 100644
> --- a/arch/s390/kvm/diag.c
> +++ b/arch/s390/kvm/diag.c
> @@ -53,6 +53,48 @@ static int __diag_time_slice_end(struct kvm_vcpu *vcpu)
> return 0;
> }
>
> +static int __diag_time_slice_end_directed(struct kvm_vcpu *vcpu)
> +{
> + struct kvm *kvm = vcpu->kvm;
> + struct kvm_vcpu *tcpu;
> + int tid;
> + int i;
> +
> + 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);
> +
> + if (tid == vcpu->vcpu_id)
> + return 0;
> +
> + kvm_for_each_vcpu(i, tcpu, kvm) {
> + if (tcpu->vcpu_id == tid) {
Can two vcpus match the same tid?
> + struct task_struct *task = NULL;
> + struct pid *pid;
> + rcu_read_lock();
> + pid = rcu_dereference(tcpu->pid);
> + if (pid)
> + task = get_pid_task(tcpu->pid, PIDTYPE_PID);
> + rcu_read_unlock();
> + if (!task)
> + break;
> + if (task->flags & PF_VCPU) {
> + put_task_struct(task);
> + break;
> + }
> + vcpu_put(vcpu);
> + if (yield_to(task, 1)) {
> + vcpu_load(vcpu);
vcpu_put()/_load()s are unneeded here, preempt notifiers will
automatically call kvm_arch_vcpu_put()/_load() if we schedule.
> + put_task_struct(task);
> + return 0;
> + }
> + vcpu_load(vcpu);
> + put_task_struct(task);
> + }
> + }
> + return 0;
> +}
> +
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index d30c835..fd98914 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -74,6 +74,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
> { "instruction_sigp_restart", VCPU_STAT(instruction_sigp_restart) },
> { "diagnose_10", VCPU_STAT(diagnose_10) },
> { "diagnose_44", VCPU_STAT(diagnose_44) },
> + { "diagnose_9c", VCPU_STAT(diagnose_9c) },
> { NULL }
> };
>
We're switching to tracepoints instead of homebrewed statistics. It's
in feature-removal-schedule.txt already. It's okay to add them now, but
please prepare for their removal.
--
error compiling committee.c: too many arguments to function
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