[Qemu-devel] PING: [PATCH v2] Do not use slow [*] expansion for GPIO creation

[Pavel Fedin]

 Hello! Long time has passed, i do not see any movements. Was it forgotten?

Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia


> -----Original Message-----
> From: address@hidden [mailto:qemu-devel-
> address@hidden On Behalf Of Paolo Bonzini
> Sent: Friday, July 31, 2015 3:39 PM
> To: Pavel Fedin; 'QEMU Developers'
> Cc: 'Andreas Färber'
> Subject: Re: [Qemu-devel] [PATCH v2] Do not use slow [*] expansion for GPIO 
> creation
> 
> 
> 
> On 31/07/2015 14:23, Pavel Fedin wrote:
> > Expansion of [*] suffix is very slow because index expansion is done using
> > trial and error strategy, starting every time from zero and retrying with
> > the next index until insertion succeeds. With large number of already added
> > properties this process takes huge amount of time (O(n^2) complexity).
> >
> > Some architectures (like ARM) use very large amount of IRQ pins in interrupt
> > controller models. This flaw makes machine startup extremely slow
> > (~20 seconds for ARM64 with 32 CPUs. This patch decreases this time down to
> > ~10 seconds.
> >
> > Also in qdev_init_gpio_out_named() memset() is now called only once for the
> > whole array instead of per-cell cleaning
> >
> > Signed-off-by: Pavel Fedin <address@hidden>
> > ---
> >  hw/core/qdev.c | 21 +++++++++++++++------
> >  1 file changed, 15 insertions(+), 6 deletions(-)
> >
> > diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> > index b2f404a..1d15736 100644
> > --- a/hw/core/qdev.c
> > +++ b/hw/core/qdev.c
> > @@ -417,17 +417,21 @@ void qdev_init_gpio_in_named(DeviceState *dev, 
> > qemu_irq_handler
> handler,
> >  {
> >      int i;
> >      NamedGPIOList *gpio_list = qdev_get_named_gpio_list(dev, name);
> > -    char *propname = g_strdup_printf("%s[*]", name ? name : 
> > "unnamed-gpio-in");
> >
> >      assert(gpio_list->num_out == 0 || !name);
> >      gpio_list->in = qemu_extend_irqs(gpio_list->in, gpio_list->num_in, 
> > handler,
> >                                       dev, n);
> >
> > +    if (!name) {
> > +        name = "unnamed-gpio-in";
> > +    }
> >      for (i = gpio_list->num_in; i < gpio_list->num_in + n; i++) {
> > +        gchar *propname = g_strdup_printf("%s[%u]", name, i);
> > +
> >          object_property_add_child(OBJECT(dev), propname,
> >                                    OBJECT(gpio_list->in[i]), &error_abort);
> > +        g_free(propname);
> >      }
> > -    g_free(propname);
> >
> >      gpio_list->num_in += n;
> >  }
> > @@ -442,20 +446,25 @@ void qdev_init_gpio_out_named(DeviceState *dev, 
> > qemu_irq *pins,
> >  {
> >      int i;
> >      NamedGPIOList *gpio_list = qdev_get_named_gpio_list(dev, name);
> > -    char *propname = g_strdup_printf("%s[*]", name ? name : 
> > "unnamed-gpio-out");
> >
> >      assert(gpio_list->num_in == 0 || !name);
> > -    gpio_list->num_out += n;
> >
> > +    if (!name) {
> > +        name = "unnamed-gpio-out";
> > +    }
> > +    memset(pins, 0, sizeof(*pins) * n);
> >      for (i = 0; i < n; ++i) {
> > -        memset(&pins[i], 0, sizeof(*pins));
> > +        gchar *propname = g_strdup_printf("%s[%u]", name,
> > +                                          gpio_list->num_out + i);
> > +
> >          object_property_add_link(OBJECT(dev), propname, TYPE_IRQ,
> >                                   (Object **)&pins[i],
> >                                   object_property_allow_set_link,
> >                                   OBJ_PROP_LINK_UNREF_ON_RELEASE,
> >                                   &error_abort);
> > +        g_free(propname);
> >      }
> > -    g_free(propname);
> > +    gpio_list->num_out += n;
> >  }
> >
> >  void qdev_init_gpio_out(DeviceState *dev, qemu_irq *pins, int n)
> >
> 
> Thanks, this looks good.  I'm not the maintainer, but I've queued it
> anyway locally so that it's not forgotten.
> 
> Paolo