Re: [PATCH] qemu-kvm: Consolidate kvm_eat_signals

Avi Kivity
2008-05-12T11:56:33Z

Jan Kiszka wrote:
>> Given that with the iothread we spend very little time processing
>> signals in vcpu threads, maybe it's better to drop the loop completely.
>> The common case is zero or one pending signals. The uncommon case of
>> two or more pending signals will be handled by the KVM_RUN ioctl
>> returning immediately with -EINTR (i.e. in the outer loop).
>>
>>
>
> You mean
>
> static void kvm_main_loop_wait(CPUState *env, int timeout)
> {
> pthread_mutex_unlock(&qemu_mutex);
> kvm_eat_signal(env, timeout);
> pthread_mutex_lock(&qemu_mutex);
> cpu_single_env = env;
>
> vcpu_info[env->cpu_index].signalled = 0;
> }
>
> ?
>

Yes. The loop was a (perhaps premature) optimization that is now
totally unnecessary, unless I'm missing something quite large.

Oh. There used to be a bug where we didn't check for a pending signal
before the first guest entry, so this would add a lot of latency
(effectively making the bug window much larger). That was only closed
in 2.6.24 (by 7e66f350).

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