Hi Anthony,
How is -no-kvm-irqchip working with the patch?
On Tue, Apr 29, 2008 at 09:28:14AM -0500, Anthony Liguori wrote:
> This patch eliminates the use of sigtimedwait() in the IO thread. To avoid
> the
> signal/select race condition, we use a pipe that we write to in the signal
> handlers. This was suggested by Rusty and seems to work well.
>
> +static int kvm_eat_signal(CPUState *env, int timeout)
> {
> struct timespec ts;
> int r, e, ret = 0;
> siginfo_t siginfo;
> + sigset_t waitset;
>
> + sigemptyset(&waitset);
> + sigaddset(&waitset, SIG_IPI);
> ts.tv_sec = timeout / 1000;
> ts.tv_nsec = (timeout % 1000) * 1000000;
> - r = sigtimedwait(&waitset->sigset, &siginfo, &ts);
> + qemu_kvm_unlock();
> + r = sigtimedwait(&waitset, &siginfo, &ts);
> + qemu_kvm_lock(env);
> + cpu_single_env = env;
This assignment seems redundant now.
> if (r == -1 && (errno == EAGAIN || errno == EINTR) && !timeout)
> return 0;
> e = errno;
> - pthread_mutex_lock(&qemu_mutex);
> if (env && vcpu)
> cpu_single_env = vcpu->env;
And this one too.
>
> @@ -263,12 +238,8 @@ static void pause_all_threads(void)
> vcpu_info[i].stop = 1;
> pthread_kill(vcpu_info[i].thread, SIG_IPI);
Make sure the IO thread has SIG_IPI blocked (those are for APIC vcpu
initialization only).
> +static void sig_aio_fd_read(void *opaque)
> +{
> + int signum;
> + ssize_t len;
> +
> + do {
> + len = read(kvm_sigfd[0], &signum, sizeof(signum));
> + } while (len == -1 && errno == EINTR);
What is the reason for this loop instead of a straight read?
Its alright to be interrupted by a signal.
> + signal(SIGUSR1, sig_aio_handler);
> + signal(SIGUSR2, sig_aio_handler);
> + signal(SIGALRM, sig_aio_handler);
> + signal(SIGIO, sig_aio_handler);
> +
> + if (pipe(kvm_sigfd) == -1)
> + abort();
perror() would be nice.
> - kvm_eat_signal(&io_signal_table, NULL, 1000);
> pthread_mutex_lock(&qemu_mutex);
> - cpu_single_env = NULL;
> - main_loop_wait(0);
> + main_loop_wait(10);
Increase that 1000 or something. Will make it easier to spot bugs.
Similarly in qemu_kvm_aio_wait().
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