Anders Melchiorsen a écrit :
> Aurelien Jarno <[EMAIL PROTECTED]> writes:
>
>> The patch below from KVM improves network transfers in a huge way.
>> wget in a MIPS target now gives me a transfer speed of up to 120
>> Mbits/s with an e1000 emulated card.
>
> Without I/O signals, qemu is relying on periodic timer events to poll
> the I/O. That seems wrong, even though it works reasonably well
> because timers are so frequent. In KVM, timers are less frequent, and
> it does not work quite as well.
>
> Here is a quick try at a more elaborate patch.
>
> It attaches a signal to all[1] file descriptors that will be used in
> select(). Also, it uses a dedicated SIGIO handler rather than
> piggybacking on the alarm handler, so alarm I/O is changed to use
> SIGALRM.
>
> I copied the handler function from the alarm case, quite frankly I do
> not quite understand what is going on. Also, I left _WIN32 out, since
> I have no idea how signals work there.
>
I have just given a tried to your patch, which looks indeed more
complete. I have made some performance measurement
(qemu-system-mips64el, 2.6.24 5kc kernel), I am getting the same
performances as with my patches on the network side, and a very small
improvement (< 3%) on the hard disk performance, but it can also be
noise (though the measurements looked quite stable).
Anybody to commit this patch?
>
> diff --git a/vl.c b/vl.c
> index c87e8bc..ff8ceef 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1148,6 +1148,25 @@ static int timer_load(QEMUFile *f, void *opaque, int
> version_id)
> return 0;
> }
>
> +#ifndef _WIN32
> +static void host_io_handler(int host_signum)
> +{
> + CPUState *env = next_cpu;
> +
> + if (env) {
> + /* stop the currently executing cpu because io occured */
> + cpu_interrupt(env, CPU_INTERRUPT_EXIT);
> +#ifdef USE_KQEMU
> + if (env->kqemu_enabled) {
> + kqemu_cpu_interrupt(env);
> + }
> +#endif
> + }
> +
> + event_pending = 1;
> +}
> +#endif
> +
> #ifdef _WIN32
> void CALLBACK host_alarm_handler(UINT uTimerID, UINT uMsg,
> DWORD_PTR dwUser, DWORD_PTR dw1, DWORD_PTR
> dw2)
> @@ -1240,7 +1259,20 @@ static uint64_t qemu_next_deadline(void)
>
> #define RTC_FREQ 1024
>
> -static void enable_sigio_timer(int fd)
> +static void enable_sigio(int fd)
> +{
> + struct sigaction act;
> +
> + sigfillset(&act.sa_mask);
> + act.sa_flags = 0;
> + act.sa_handler = host_io_handler;
> +
> + sigaction(SIGIO, &act, NULL);
> + fcntl(fd, F_SETFL, O_ASYNC);
> + fcntl(fd, F_SETOWN, getpid());
> +}
> +
> +static void enable_sigalrm(int fd)
> {
> struct sigaction act;
>
> @@ -1249,8 +1281,9 @@ static void enable_sigio_timer(int fd)
> act.sa_flags = 0;
> act.sa_handler = host_alarm_handler;
>
> - sigaction(SIGIO, &act, NULL);
> + sigaction(SIGALRM, &act, NULL);
> fcntl(fd, F_SETFL, O_ASYNC);
> + fcntl(fd, F_SETSIG, SIGALRM);
> fcntl(fd, F_SETOWN, getpid());
> }
>
> @@ -1287,7 +1320,7 @@ static int hpet_start_timer(struct qemu_alarm_timer *t)
> if (r < 0)
> goto fail;
>
> - enable_sigio_timer(fd);
> + enable_sigalrm(fd);
> t->priv = (void *)(long)fd;
>
> return 0;
> @@ -1325,7 +1358,7 @@ static int rtc_start_timer(struct qemu_alarm_timer *t)
> return -1;
> }
>
> - enable_sigio_timer(rtc_fd);
> + enable_sigalrm(rtc_fd);
>
> t->priv = (void *)(long)rtc_fd;
>
> @@ -5481,6 +5514,10 @@ int qemu_set_fd_handler2(int fd,
> return -1;
> ioh->next = first_io_handler;
> first_io_handler = ioh;
> +#ifndef _WIN32
> + enable_sigio(fd);
> +#endif
> +
> found:
> ioh->fd = fd;
> ioh->fd_read_poll = fd_read_poll;
>
--
.''`. Aurelien Jarno | GPG: 1024D/F1BCDB73
: :' : Debian developer | Electrical Engineer
`. `' [EMAIL PROTECTED] | [EMAIL PROTECTED]
`- people.debian.org/~aurel32 | www.aurel32.net
