On 01/05/2011 11:40 AM, Xiao Guangrong wrote:
Now, we have 'vcpu->guest_mode' to judge whether need to send
ipi to other cpus, this way is very exact, so checking request
bit is needless, then we can drop the spinlock let it's collateral

Clever.

@@ -147,11 +147,9 @@ static bool make_all_cpus_request(struct kvm *kvm, 
unsigned int req)

        zalloc_cpumask_var(&cpus, GFP_ATOMIC);

-       raw_spin_lock(&kvm->requests_lock);
-       me = smp_processor_id();
+       me = get_cpu();
        kvm_for_each_vcpu(i, vcpu, kvm) {
-               if (kvm_make_check_request(req, vcpu))
-                       continue;
+               kvm_make_request(req, vcpu);
                cpu = vcpu->cpu;
                if (cpus != NULL&&  cpu != -1&&  cpu != me&&
                atomic_read(&vcpu->guest_mode))
@@ -163,7 +161,7 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned 
int req)
                smp_call_function_many(cpus, ack_flush, NULL, 1);
        else
                called = false;
-       raw_spin_unlock(&kvm->requests_lock);
+       put_cpu();
        free_cpumask_var(cpus);
        return called;
  }

Maybe we can drop 'cpu != me' and then we don't need to disable preemption?

Can be done in a later patch.

Anyway, I really like this, requests_lock is an ugly wart.

--
error compiling committee.c: too many arguments to function

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