δΊ 2014/1/6 2:02, Peter Lieven ει:
> 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.
>
> The following artifical test (just the bitmap operation part) running
> vnc_update_client 65536 times on a 2560x2048 surface illustrates the
> performance difference:
>
> All bits clean - vnc_update_client_new: 0.07 secs
> vnc_update_client_old: 10.98 secs
>
> All bits dirty - vnc_update_client_new: 11.26 secs
> vnc_update_client_old: 20.19 secs
>
> Few bits dirty - vnc_update_client_new: 0.08 secs
> vnc_update_client_old: 10.98 secs
>
> The case for all bits dirty is still rather slow, this
> is due to the implementation of find_and_clear_dirty_height.
> This will be addresses in a separate patch.
>
> Signed-off-by: Peter Lieven <p...@kamp.de>
> ---
> ui/vnc.c | 154
> +++++++++++++++++++++++++++++++++-----------------------------
> ui/vnc.h | 4 ++
> 2 files changed, 87 insertions(+), 71 deletions(-)
>
> diff --git a/ui/vnc.c b/ui/vnc.c
> index 1d2aa1a..6a0c03e 100644
> --- a/ui/vnc.c
> +++ b/ui/vnc.c
> @@ -572,6 +572,14 @@ 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 y;\
> + memset(bitmap, 0x00, sizeof(bitmap));\
> + for (y = 0; y < h; y++) {\
> + bitmap_set(bitmap[y], 0, w / VNC_DIRTY_PIXELS_PER_BIT);\
Will it be a problem when vnc's width % VNC_DIRTY_PIXELS_PER_BIT != 0?
Although it is a rare case, but I think it is better round it up, since
"v" and "VNC_DIRTY_PIXELS_PER_BIT" are variables. A macro computing it
would be nice:
#define VNC_DIRTY_BITS_FROM_WIDTH(w) (w + VNC_DIRTY_PIXELS_PER_BIT - 1/
VNC_DIRTY_PIXELS_PER_BIT)
#define VNC_DIRTY_BITS (VNC_DIRTY_BITS_FROM_WIDTH(VNC_MAX_WIDTH)
then here:
bitmap_set(bitmap[y], 0, VNC_DIRTY_BITS_FROM_WIDTH(w));
Or simply warn or coredump when v % VNC_DIRTY_PIXELS_PER_BIT != 0.
Also, in vnc.h:
/* VNC_MAX_WIDTH must be a multiple of 16. */
#define VNC_MAX_WIDTH 2560
#define VNC_MAX_HEIGHT 2048
Maybe it should be updated as:
/* VNC_MAX_WIDTH must be a multiple of VNC_DIRTY_PIXELS_PER_BIT. */
> + } \
> + }
>
> static void vnc_dpy_switch(DisplayChangeListener *dcl,
> DisplaySurface *surface)
> @@ -597,7 +605,9 @@ 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 +615,9 @@ 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));
> }
> }
>
> @@ -889,10 +901,9 @@ static int vnc_update_client(VncState *vs, int has_dirty)
> VncDisplay *vd = vs->vd;
> VncJob *job;
> int y;
> - int width, height;
> + int height;
> int n = 0;
>
> -
> if (vs->output.offset && !vs->audio_cap && !vs->force_update)
> /* kernel send buffers are full -> drop frames to throttle */
> return 0;
> @@ -908,39 +919,27 @@ static int vnc_update_client(VncState *vs, int
> has_dirty)
> */
> job = vnc_job_new(vs);
>
> - 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++) {
> - int x;
> - int last_x = -1;
> - for (x = 0; 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);
> - }
> - 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);
> + y = 0;
> + for (;;) {
> + int x, h;
> + unsigned long x2;
> + unsigned long offset = find_next_bit((unsigned long *)
> &vs->dirty,
> + height * VNC_DIRTY_BPL(vs),
> + y * VNC_DIRTY_BPL(vs));
> + if (offset == height * VNC_DIRTY_BPL(vs)) {
> + /* no more dirty bits */
> + break;
> }
> + y = offset / VNC_DIRTY_BPL(vs);
> + x = offset % VNC_DIRTY_BPL(vs);
> + x2 = find_next_zero_bit((unsigned long *) &vs->dirty[y],
> + VNC_DIRTY_BPL(vs), x);
> + bitmap_clear(vs->dirty[y], x, x2 - x);
> + h = find_and_clear_dirty_height(vs, y, x, x2, height);
> + n += vnc_job_add_rect(job, x * VNC_DIRTY_PIXELS_PER_BIT, y,
> + (x2 - x) * VNC_DIRTY_PIXELS_PER_BIT, h);
> }
Minor comments:
VNC_DIRTY_BPL(vs) is accessing memory by pointer, should we use a
variable instead of VNC_DIRTY_BPL(vs) in every place, in case of
compiler didn't optimize it for us?
>
> vnc_job_push(job);
> @@ -2678,8 +2677,8 @@ 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;
Any reason that rename those variable?
> + int guest_stride = 0, server_stride;
> int cmp_bytes;
> VncState *vs;
> int has_dirty = 0;
> @@ -2704,44 +2703,57 @@ 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;
> -
> - 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;
> + } else {
> + guest_row0 = (uint8_t *)pixman_image_get_data(vd->guest.fb);
> + guest_stride = pixman_image_get_stride(vd->guest.fb);
> + }
> + server_row0 = (uint8_t *)pixman_image_get_data(vd->server);
> + 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_BPL(&vd->guest),
> + y * VNC_DIRTY_BPL(&vd->guest));
> + if (offset == height * VNC_DIRTY_BPL(&vd->guest)) {
> + /* no more dirty bits */
> + break;
> + }
> + y = offset / VNC_DIRTY_BPL(&vd->guest);
>
> - 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++;
> + server_ptr = server_row0 + y * server_stride;
> +
> + 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_BPL(&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..07e1f59 100644
> --- a/ui/vnc.h
> +++ b/ui/vnc.h
> @@ -88,6 +88,10 @@ 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_BPL (BPL = bits per line) might be greater than
> + * VNC_DIRTY_BITS due to alignment */
> +#define VNC_DIRTY_BPL(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)
>
