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ui/gtk: limit virtual console max update interval 

Limit the virtual console maximum update interval to
GUI_REFRESH_INTERVAL_DEFAULT. This papers over a integer
overflow bug in gtk3 on Windows where the reported monitor
refresh frequency can be much smaller than the real refresh
frequency.

The gtk bug report can be found here:
https://gitlab.gnome.org/GNOME/gtk/-/issues/3394

On my Windows 10 system gtk reports a monitor refresh rate of
1.511Hz instead of 60.031Hz and slows down the screen update
rate in qemu to a crawl. Provided you are affected by the gtk
bug on Windows, these are the steps to reproduce the issue:

Start qemu with -display gtk and activate all qemu virtual
consoles and notice the reduced qemu refresh rate. Activating
all virtual consoles is necessary, because gui_update() in
ui/console.c uses the minimum of all display change listeners
update interval and not yet activated virtual consoles report
the default update interval (30ms).

Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Message-Id: <20201213165724.13418-3-vr_qemu@t-online.de>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Volker Rümelin 2020-12-13 17:57:24 +01:00 committed by Gerd Hoffmann
parent 0431e369b0
commit 3c4b8f8310
1 changed files with 11 additions and 11 deletions
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22
ui/gtk.c
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@ -749,10 +749,10 @@ static void gd_resize_event(GtkGLArea *area,
#endif
/*
* If available, return the refresh rate of the display in milli-Hertz,
* else return 0.
* If available, return the update interval of the monitor in ms,
* else return 0 (the default update interval).
*/
static int gd_refresh_rate_millihz(GtkWidget *widget)
static int gd_monitor_update_interval(GtkWidget *widget)
{
#ifdef GDK_VERSION_3_22
GdkWindow *win = gtk_widget_get_window(widget);
@ -760,8 +760,13 @@ static int gd_refresh_rate_millihz(GtkWidget *widget)
if (win) {
GdkDisplay *dpy = gtk_widget_get_display(widget);
GdkMonitor *monitor = gdk_display_get_monitor_at_window(dpy, win);
int refresh_rate = gdk_monitor_get_refresh_rate(monitor); /* [mHz] */
return gdk_monitor_get_refresh_rate(monitor);
if (refresh_rate) {
/* T = 1 / f = 1 [s*Hz] / f = 1000*1000 [ms*mHz] / f */
return MIN(1000 * 1000 / refresh_rate,
GUI_REFRESH_INTERVAL_DEFAULT);
}
}
#endif
return 0;
@ -774,7 +779,6 @@ static gboolean gd_draw_event(GtkWidget *widget, cairo_t *cr, void *opaque)
int mx, my;
int ww, wh;
int fbw, fbh;
int refresh_rate_millihz;
#if defined(CONFIG_OPENGL)
if (vc->gfx.gls) {
@ -795,12 +799,8 @@ static gboolean gd_draw_event(GtkWidget *widget, cairo_t *cr, void *opaque)
return FALSE;
}
refresh_rate_millihz = gd_refresh_rate_millihz(vc->window ?
vc->window : s->window);
if (refresh_rate_millihz) {
/* T = 1 / f = 1 [s*Hz] / f = 1000*1000 [ms*mHz] / f */
vc->gfx.dcl.update_interval = 1000 * 1000 / refresh_rate_millihz;
}
vc->gfx.dcl.update_interval =
gd_monitor_update_interval(vc->window ? vc->window : s->window);
fbw = surface_width(vc->gfx.ds);
fbh = surface_height(vc->gfx.ds);