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[Qemu-devel] [PATCH 2/3] ui/vnc: optimize dirty bitmap tracking
From: |
Peter Lieven |
Subject: |
[Qemu-devel] [PATCH 2/3] ui/vnc: optimize dirty bitmap tracking |
Date: |
Mon, 18 Nov 2013 09:17:20 +0100 |
vnc_update_client currently scans the dirty bitmap of each client
bitwise which is a very costly operation if only few bits are dirty.
vnc_refresh_server_surface does almost the same.
this patch optimizes both by utilizing the heavily optimized
function find_next_bit to find the offset of the next dirty
bit in the dirty bitmaps.
Signed-off-by: Peter Lieven <address@hidden>
---
ui/vnc.c | 146 ++++++++++++++++++++++++++++++++++++++------------------------
ui/vnc.h | 3 ++
2 files changed, 92 insertions(+), 57 deletions(-)
diff --git a/ui/vnc.c b/ui/vnc.c
index 67b1f75..edf33be 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -572,6 +572,16 @@ void *vnc_server_fb_ptr(VncDisplay *vd, int x, int y)
ptr += x * VNC_SERVER_FB_BYTES;
return ptr;
}
+/* this sets only the visible pixels of a dirty bitmap */
+#define VNC_SET_VISIBLE_PIXELS_DIRTY(bitmap, w, h) {\
+ int x, y;\
+ memset(bitmap, 0x00, sizeof(bitmap));\
+ for (y = 0; y < h; y++) {\
+ for (x = 0; x < w / VNC_DIRTY_PIXELS_PER_BIT; x++) {\
+ set_bit(x, bitmap[y]);\
+ } \
+ } \
+ }
static void vnc_dpy_switch(DisplayChangeListener *dcl,
DisplaySurface *surface)
@@ -597,7 +607,9 @@ static void vnc_dpy_switch(DisplayChangeListener *dcl,
qemu_pixman_image_unref(vd->guest.fb);
vd->guest.fb = pixman_image_ref(surface->image);
vd->guest.format = surface->format;
- memset(vd->guest.dirty, 0xFF, sizeof(vd->guest.dirty));
+ VNC_SET_VISIBLE_PIXELS_DIRTY(vd->guest.dirty,
+ surface_width(vd->ds),
+ surface_height(vd->ds));
QTAILQ_FOREACH(vs, &vd->clients, next) {
vnc_colordepth(vs);
@@ -605,7 +617,9 @@ static void vnc_dpy_switch(DisplayChangeListener *dcl,
if (vs->vd->cursor) {
vnc_cursor_define(vs);
}
- memset(vs->dirty, 0xFF, sizeof(vs->dirty));
+ VNC_SET_VISIBLE_PIXELS_DIRTY(vs->dirty,
+ surface_width(vd->ds),
+ surface_height(vd->ds));
}
}
@@ -882,6 +896,14 @@ static int vnc_update_client_sync(VncState *vs, int
has_dirty)
return ret;
}
+#define VNC_CLIENT_UPDATE_RECT() \
+ if (last_x != -1) {\
+ int h = find_and_clear_dirty_height(vs, y, last_x, x, height);\
+ n += vnc_job_add_rect(job,\
+ last_x * VNC_DIRTY_PIXELS_PER_BIT, y,\
+ (x - last_x) * VNC_DIRTY_PIXELS_PER_BIT, h);\
+ }
+
static int vnc_update_client(VncState *vs, int has_dirty)
{
if (vs->need_update && vs->csock != -1) {
@@ -910,35 +932,32 @@ static int vnc_update_client(VncState *vs, int has_dirty)
width = MIN(pixman_image_get_width(vd->server), vs->client_width);
height = MIN(pixman_image_get_height(vd->server), vs->client_height);
- for (y = 0; y < height; y++) {
+ y = 0;
+ for (;;) {
int x;
int last_x = -1;
- for (x = 0; x < width / VNC_DIRTY_PIXELS_PER_BIT; x++) {
+ unsigned long offset = find_next_bit((unsigned long *) &vs->dirty,
+ height *
VNC_DIRTY_BITS_PER_LINE(vs),
+ y *
VNC_DIRTY_BITS_PER_LINE(vs));
+ if (offset == height * VNC_DIRTY_BITS_PER_LINE(vs)) {
+ /* no more dirty bits */
+ break;
+ }
+ y = offset / VNC_DIRTY_BITS_PER_LINE(vs);
+
+ for (x = offset % VNC_DIRTY_BITS_PER_LINE(vs);
+ x < width / VNC_DIRTY_PIXELS_PER_BIT; x++) {
if (test_and_clear_bit(x, vs->dirty[y])) {
if (last_x == -1) {
last_x = x;
}
} else {
- if (last_x != -1) {
- int h = find_and_clear_dirty_height(vs, y, last_x, x,
- height);
-
- n += vnc_job_add_rect(job,
- last_x *
VNC_DIRTY_PIXELS_PER_BIT,
- y,
- (x - last_x) *
VNC_DIRTY_PIXELS_PER_BIT,
- h);
- }
+ VNC_CLIENT_UPDATE_RECT();
last_x = -1;
}
}
- if (last_x != -1) {
- int h = find_and_clear_dirty_height(vs, y, last_x, x, height);
- n += vnc_job_add_rect(job, last_x * VNC_DIRTY_PIXELS_PER_BIT,
- y,
- (x - last_x) * VNC_DIRTY_PIXELS_PER_BIT,
- h);
- }
+ VNC_CLIENT_UPDATE_RECT();
+ y++;
}
vnc_job_push(job);
@@ -2676,8 +2695,8 @@ static int vnc_refresh_server_surface(VncDisplay *vd)
int width = pixman_image_get_width(vd->guest.fb);
int height = pixman_image_get_height(vd->guest.fb);
int y;
- uint8_t *guest_row;
- uint8_t *server_row;
+ uint8_t *guest_row0 = NULL, *server_row0;
+ int guest_stride, server_stride;
int cmp_bytes;
VncState *vs;
int has_dirty = 0;
@@ -2702,44 +2721,57 @@ static int vnc_refresh_server_surface(VncDisplay *vd)
if (vd->guest.format != VNC_SERVER_FB_FORMAT) {
int width = pixman_image_get_width(vd->server);
tmpbuf = qemu_pixman_linebuf_create(VNC_SERVER_FB_FORMAT, width);
- }
- guest_row = (uint8_t *)pixman_image_get_data(vd->guest.fb);
- server_row = (uint8_t *)pixman_image_get_data(vd->server);
- for (y = 0; y < height; y++) {
- if (!bitmap_empty(vd->guest.dirty[y], VNC_DIRTY_BITS)) {
- int x;
- uint8_t *guest_ptr;
- uint8_t *server_ptr;
+ } else {
+ guest_row0 = (uint8_t *)pixman_image_get_data(vd->guest.fb);
+ }
+ server_row0 = (uint8_t *)pixman_image_get_data(vd->server);
+ guest_stride = pixman_image_get_stride(vd->guest.fb);
+ server_stride = pixman_image_get_stride(vd->server);
+
+ y = 0;
+ for (;;) {
+ int x;
+ uint8_t *guest_ptr, *server_ptr;
+ unsigned long offset = find_next_bit((unsigned long *)
&vd->guest.dirty,
+ height *
VNC_DIRTY_BITS_PER_LINE(&vd->guest),
+ y *
VNC_DIRTY_BITS_PER_LINE(&vd->guest));
+ if (offset == height * VNC_DIRTY_BITS_PER_LINE(&vd->guest)) {
+ /* no more dirty bits */
+ break;
+ }
+ y = offset / VNC_DIRTY_BITS_PER_LINE(&vd->guest);
- if (vd->guest.format != VNC_SERVER_FB_FORMAT) {
- qemu_pixman_linebuf_fill(tmpbuf, vd->guest.fb, width, 0, y);
- guest_ptr = (uint8_t *)pixman_image_get_data(tmpbuf);
- } else {
- guest_ptr = guest_row;
- }
- server_ptr = server_row;
+ server_ptr = server_row0 + y * server_stride;
- for (x = 0; x + VNC_DIRTY_PIXELS_PER_BIT - 1 < width;
- x += VNC_DIRTY_PIXELS_PER_BIT, guest_ptr += cmp_bytes,
- server_ptr += cmp_bytes) {
- if (!test_and_clear_bit((x / VNC_DIRTY_PIXELS_PER_BIT),
- vd->guest.dirty[y])) {
- continue;
- }
- if (memcmp(server_ptr, guest_ptr, cmp_bytes) == 0) {
- continue;
- }
- memcpy(server_ptr, guest_ptr, cmp_bytes);
- if (!vd->non_adaptive)
- vnc_rect_updated(vd, x, y, &tv);
- QTAILQ_FOREACH(vs, &vd->clients, next) {
- set_bit((x / VNC_DIRTY_PIXELS_PER_BIT), vs->dirty[y]);
- }
- has_dirty++;
+ if (vd->guest.format != VNC_SERVER_FB_FORMAT) {
+ qemu_pixman_linebuf_fill(tmpbuf, vd->guest.fb, width, 0, y);
+ guest_ptr = (uint8_t *)pixman_image_get_data(tmpbuf);
+ } else {
+ guest_ptr = guest_row0 + y * guest_stride;
+ }
+
+ for (x = offset % VNC_DIRTY_BITS_PER_LINE(&vd->guest);
+ x + VNC_DIRTY_PIXELS_PER_BIT - 1 < width;
+ x += VNC_DIRTY_PIXELS_PER_BIT, guest_ptr += cmp_bytes,
+ server_ptr += cmp_bytes) {
+ if (!test_and_clear_bit((x / VNC_DIRTY_PIXELS_PER_BIT),
+ vd->guest.dirty[y])) {
+ continue;
+ }
+ if (memcmp(server_ptr, guest_ptr, cmp_bytes) == 0) {
+ continue;
+ }
+ memcpy(server_ptr, guest_ptr, cmp_bytes);
+ if (!vd->non_adaptive) {
+ vnc_rect_updated(vd, x, y, &tv);
}
+ QTAILQ_FOREACH(vs, &vd->clients, next) {
+ set_bit((x / VNC_DIRTY_PIXELS_PER_BIT), vs->dirty[y]);
+ }
+ has_dirty++;
}
- guest_row += pixman_image_get_stride(vd->guest.fb);
- server_row += pixman_image_get_stride(vd->server);
+
+ y++;
}
qemu_pixman_image_unref(tmpbuf);
return has_dirty;
diff --git a/ui/vnc.h b/ui/vnc.h
index 4a8f33c..82c8ea8 100644
--- a/ui/vnc.h
+++ b/ui/vnc.h
@@ -88,6 +88,9 @@ typedef void VncSendHextileTile(VncState *vs,
/* VNC_DIRTY_BITS is the number of bits in the dirty bitmap. */
#define VNC_DIRTY_BITS (VNC_MAX_WIDTH / VNC_DIRTY_PIXELS_PER_BIT)
+/* VNC_DIRTY_BITS_PER_LINE might be greater than VNC_DIRTY_BITS due to
alignment */
+#define VNC_DIRTY_BITS_PER_LINE(x) (sizeof((x)->dirty) / VNC_MAX_HEIGHT *
BITS_PER_BYTE)
+
#define VNC_STAT_RECT 64
#define VNC_STAT_COLS (VNC_MAX_WIDTH / VNC_STAT_RECT)
#define VNC_STAT_ROWS (VNC_MAX_HEIGHT / VNC_STAT_RECT)
--
1.7.9.5