[Qemu-devel] [PATCH 2/2] optimize screendump for the common non-switch case

[Gerd Hoffmann <kraxel@redhat.com>]

switch console only if needed, also pass down whenever the console was
switched or not because a displaysurface redraw is only needed in case
the console was switched.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 console.c       |   10 +++++++---
 console.h       |    2 +-
 hw/qxl.c        |    4 ++--
 hw/vga.c        |   10 ++++++----
 hw/vmware_vga.c |    4 ++--
 5 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/console.c b/console.c
index 135394f..b3bd14a 100644
--- a/console.c
+++ b/console.c
@@ -176,17 +176,21 @@ void vga_hw_invalidate(void)
 void vga_hw_screen_dump(const char *filename)
 {
     TextConsole *previous_active_console;
+    bool cswitch;
 
     previous_active_console = active_console;
+    cswitch = previous_active_console && previous_active_console->index != 0;
 
     /* There is currently no way of specifying which screen we want to dump,
        so always dump the first one.  */
-    console_select(0);
+    if (cswitch) {
+        console_select(0);
+    }
     if (consoles[0] && consoles[0]->hw_screen_dump) {
-        consoles[0]->hw_screen_dump(consoles[0]->hw, filename);
+        consoles[0]->hw_screen_dump(consoles[0]->hw, filename, cswitch);
     }
 
-    if (previous_active_console) {
+    if (cswitch) {
         console_select(previous_active_console->index);
     }
 }
diff --git a/console.h b/console.h
index 6ba0d5d..1fc8ea3 100644
--- a/console.h
+++ b/console.h
@@ -340,7 +340,7 @@ static inline void console_write_ch(console_ch_t *dest, uint32_t ch)
 
 typedef void (*vga_hw_update_ptr)(void *);
 typedef void (*vga_hw_invalidate_ptr)(void *);
-typedef void (*vga_hw_screen_dump_ptr)(void *, const char *);
+typedef void (*vga_hw_screen_dump_ptr)(void *, const char *, bool cswitch);
 typedef void (*vga_hw_text_update_ptr)(void *, console_ch_t *);
 
 DisplayState *graphic_console_init(vga_hw_update_ptr update,
diff --git a/hw/qxl.c b/hw/qxl.c
index e38bb29..f4c68ab 100644
--- a/hw/qxl.c
+++ b/hw/qxl.c
@@ -1438,7 +1438,7 @@ static void qxl_hw_invalidate(void *opaque)
     vga->invalidate(vga);
 }
 
-static void qxl_hw_screen_dump(void *opaque, const char *filename)
+static void qxl_hw_screen_dump(void *opaque, const char *filename, bool cswitch)
 {
     PCIQXLDevice *qxl = opaque;
     VGACommonState *vga = &qxl->vga;
@@ -1450,7 +1450,7 @@ static void qxl_hw_screen_dump(void *opaque, const char *filename)
         ppm_save(filename, qxl->ssd.ds->surface);
         break;
     case QXL_MODE_VGA:
-        vga->screen_dump(vga, filename);
+        vga->screen_dump(vga, filename, cswitch);
         break;
     default:
         break;
diff --git a/hw/vga.c b/hw/vga.c
index f8f30f8..5994f43 100644
--- a/hw/vga.c
+++ b/hw/vga.c
@@ -162,7 +162,7 @@ static uint32_t expand4[256];
 static uint16_t expand2[256];
 static uint8_t expand4to8[16];
 
-static void vga_screen_dump(void *opaque, const char *filename);
+static void vga_screen_dump(void *opaque, const char *filename, bool cswitch);
 
 static void vga_update_memory_access(VGACommonState *s)
 {
@@ -2407,11 +2407,13 @@ int ppm_save(const char *filename, struct DisplaySurface *ds)
 
 /* save the vga display in a PPM image even if no display is
    available */
-static void vga_screen_dump(void *opaque, const char *filename)
+static void vga_screen_dump(void *opaque, const char *filename, bool cswitch)
 {
     VGACommonState *s = opaque;
 
-    vga_invalidate_display(s);
-    vga_hw_update();
+    if (cswitch) {
+        vga_invalidate_display(s);
+        vga_hw_update();
+    }
     ppm_save(filename, s->ds->surface);
 }
diff --git a/hw/vmware_vga.c b/hw/vmware_vga.c
index f8afa3c..142d9f4 100644
--- a/hw/vmware_vga.c
+++ b/hw/vmware_vga.c
@@ -1003,11 +1003,11 @@ static void vmsvga_invalidate_display(void *opaque)
 
 /* save the vga display in a PPM image even if no display is
    available */
-static void vmsvga_screen_dump(void *opaque, const char *filename)
+static void vmsvga_screen_dump(void *opaque, const char *filename, bool cswitch)
 {
     struct vmsvga_state_s *s = opaque;
     if (!s->enable) {
-        s->vga.screen_dump(&s->vga, filename);
+        s->vga.screen_dump(&s->vga, filename, cswitch);
         return;
     }
 
-- 
1.7.1