[PATCH 3/4] modesetting: Implement a double-buffered shadow mode
Adam Jackson
ajax at redhat.com
Wed Jul 22 09:14:08 PDT 2015
Server GPUs often have a VNC feature attached to allow remote console.
The controller implementing this feature is usually not very powerful,
and we can easily swamp it with work. This is made somewhat worse by
damage over-reporting the size of the dirty region, and a whole lot
worse by applications (or shells) that update the screen with identical
pixel content as was already there.
Fix this by double-buffering the shadow fb, using memcmp to identify
dirty tiles on each update pass. Since both shadows are in host memory
the memcmp is cheap, and worth it given the win in network bandwidth.
The tile size is somewhat arbitrarily chosen to be one cacheline wide at
32bpp on Intel Core.
By default we enable this behaviour for (a subset of) known server GPUs;
the heuristic could use work.
Signed-off-by: Adam Jackson <ajax at redhat.com>
---
hw/xfree86/drivers/modesetting/driver.c | 128 ++++++++++++++++++++++-
hw/xfree86/drivers/modesetting/drmmode_display.c | 13 +++
hw/xfree86/drivers/modesetting/drmmode_display.h | 2 +
3 files changed, 138 insertions(+), 5 deletions(-)
diff --git a/hw/xfree86/drivers/modesetting/driver.c b/hw/xfree86/drivers/modesetting/driver.c
index 68a865f..58ac420 100644
--- a/hw/xfree86/drivers/modesetting/driver.c
+++ b/hw/xfree86/drivers/modesetting/driver.c
@@ -125,6 +125,7 @@ typedef enum {
OPTION_SHADOW_FB,
OPTION_ACCEL_METHOD,
OPTION_PAGEFLIP,
+ OPTION_DOUBLE_SHADOW,
} modesettingOpts;
static const OptionInfoRec Options[] = {
@@ -133,6 +134,7 @@ static const OptionInfoRec Options[] = {
{OPTION_SHADOW_FB, "ShadowFB", OPTV_BOOLEAN, {0}, FALSE},
{OPTION_ACCEL_METHOD, "AccelMethod", OPTV_STRING, {0}, FALSE},
{OPTION_PAGEFLIP, "PageFlip", OPTV_BOOLEAN, {0}, FALSE},
+ {OPTION_DOUBLE_SHADOW, "DoubleShadow", OPTV_BOOLEAN, {0}, FALSE},
{-1, NULL, OPTV_NONE, {0}, FALSE}
};
@@ -651,6 +653,32 @@ try_enable_glamor(ScrnInfoPtr pScrn)
#endif
}
+static Bool
+msShouldDoubleShadow(ScrnInfoPtr pScrn, modesettingPtr ms)
+{
+ Bool ret = FALSE, asked;
+ int from;
+ drmVersionPtr v = drmGetVersion(ms->fd);
+
+ if (!strcmp(v->name, "mgag200") ||
+ !strcmp(v->name, "ast")) /* XXX || rn50 */
+ ret = TRUE;
+
+ drmFreeVersion(v);
+
+ asked = xf86GetOptValBool(ms->Options, OPTION_DOUBLE_SHADOW, &ret);
+
+ if (asked)
+ from = X_CONFIG;
+ else
+ from = X_INFO;
+
+ xf86DrvMsg(pScrn->scrnIndex, from,
+ "Double-buffered shadow updates: %s", ret ? "on" : "off");
+
+ return ret;
+}
+
#ifndef DRM_CAP_CURSOR_WIDTH
#define DRM_CAP_CURSOR_WIDTH 0x8
#endif
@@ -855,6 +883,7 @@ PreInit(ScrnInfoPtr pScrn, int flags)
ms->drmmode.shadow_enable ? "YES" : "NO");
ms->drmmode.pageflip = FALSE;
+ ms->drmmode.shadow_enable2 = msShouldDoubleShadow(pScrn, ms);
}
if (drmmode_pre_init(pScrn, &ms->drmmode, pScrn->bitsPerPixel / 8) == FALSE) {
@@ -913,10 +942,91 @@ msShadowWindow(ScreenPtr screen, CARD32 row, CARD32 offset, int mode,
return ((uint8_t *) ms->drmmode.front_bo.dumb->ptr + row * stride + offset);
}
+/* somewhat arbitrary tile size, in pixels */
+#define TILE 16
+
+static int
+msUpdateIntersect(modesettingPtr ms, shadowBufPtr pBuf, BoxPtr box,
+ xRectangle *prect)
+{
+ int i, dirty = 0, stride = pBuf->pPixmap->devKind, cpp = ms->drmmode.cpp;
+ int width = (box->x2 - box->x1) * cpp;
+ unsigned char *old, *new;
+
+ old = ms->drmmode.shadow_fb2;
+ old += (box->y1 * stride) + (box->x1 * cpp);
+ new = ms->drmmode.shadow_fb;
+ new += (box->y1 * stride) + (box->x1 * cpp);
+
+ for (i = box->y2 - box->y1 - 1; i >= 0; i--) {
+ unsigned char *o = old + i * stride,
+ *n = new + i * stride;
+ if (memcmp(o, n, width) != 0) {
+ dirty = 1;
+ memcpy(o, n, width);
+ }
+ }
+
+ if (dirty) {
+ prect->x = box->x1;
+ prect->y = box->y1;
+ prect->width = box->x2 - box->x1;
+ prect->height = box->y2 - box->y1;
+ }
+
+ return dirty;
+}
+
static void
msUpdatePacked(ScreenPtr pScreen, shadowBufPtr pBuf)
{
- shadowUpdatePacked(pScreen, pBuf);
+ ScrnInfoPtr pScrn = xf86ScreenToScrn(pScreen);
+ modesettingPtr ms = modesettingPTR(pScrn);
+ Bool use_ms_shadow = ms->drmmode.force_24_32 && pScrn->bitsPerPixel == 32;
+
+ if (ms->drmmode.shadow_enable2 && ms->drmmode.shadow_fb2) do {
+ RegionPtr damage = DamageRegion(pBuf->pDamage), tiles;
+ BoxPtr extents = RegionExtents(damage);
+ xRectangle *prect;
+ int nrects;
+ int i, j, tx1, tx2, ty1, ty2;
+
+ tx1 = extents->x1 / TILE;
+ tx2 = (extents->x2 + TILE - 1) / TILE;
+ ty1 = extents->y1 / TILE;
+ ty2 = (extents->y2 + TILE - 1) / TILE;
+
+ nrects = (tx2 - tx1) * (ty2 - ty1);
+ if (!(prect = calloc(nrects, sizeof(xRectangle))))
+ break;
+
+ nrects = 0;
+ for (j = ty2; j >= ty1; j--) {
+ for (i = tx2; i >= tx1; i--) {
+ BoxRec box;
+
+ box.x1 = max(i * TILE, extents->x1);
+ box.y1 = max(j * TILE, extents->y1);
+ box.x2 = min((i+1) * TILE, extents->x2);
+ box.y2 = min((j+1) * TILE, extents->y2);
+
+ if (RegionContainsRect(damage, &box) != rgnOUT) {
+ if (msUpdateIntersect(ms, pBuf, &box, prect + nrects)) {
+ nrects++;
+ }
+ }
+ }
+ }
+
+ tiles = RegionFromRects(nrects, prect, CT_NONE);
+ RegionIntersect(damage, damage, tiles);
+ RegionDestroy(tiles);
+ } while (0);
+
+ if (use_ms_shadow)
+ ms_shadowUpdate32to24(pScreen, pBuf);
+ else
+ shadowUpdatePacked(pScreen, pBuf);
}
static Bool
@@ -928,7 +1038,6 @@ CreateScreenResources(ScreenPtr pScreen)
Bool ret;
void *pixels = NULL;
int err;
- Bool use_ms_shadow = ms->drmmode.force_24_32 && pScrn->bitsPerPixel == 32;
pScreen->CreateScreenResources = ms->createScreenResources;
ret = pScreen->CreateScreenResources(pScreen);
@@ -956,13 +1065,20 @@ CreateScreenResources(ScreenPtr pScreen)
if (ms->drmmode.shadow_enable)
pixels = ms->drmmode.shadow_fb;
+ if (ms->drmmode.shadow_enable2) {
+ ms->drmmode.shadow_fb2 = calloc(1, pScrn->displayWidth * pScrn->virtualY * ((pScrn->bitsPerPixel + 7) >> 3));
+ if (!ms->drmmode.shadow_fb2)
+ ms->drmmode.shadow_enable2 = FALSE;
+ else
+ pixels = ms->drmmode.shadow_fb2;
+ }
+
if (!pScreen->ModifyPixmapHeader(rootPixmap, -1, -1, -1, -1, -1, pixels))
FatalError("Couldn't adjust screen pixmap\n");
if (ms->drmmode.shadow_enable) {
- if (!shadowAdd(pScreen, rootPixmap,
- use_ms_shadow ? ms_shadowUpdate32to24 : msUpdatePacked,
- msShadowWindow, 0, 0))
+ if (!shadowAdd(pScreen, rootPixmap, msUpdatePacked, msShadowWindow,
+ 0, 0))
return FALSE;
}
@@ -1311,6 +1427,8 @@ CloseScreen(ScreenPtr pScreen)
shadowRemove(pScreen, pScreen->GetScreenPixmap(pScreen));
free(ms->drmmode.shadow_fb);
ms->drmmode.shadow_fb = NULL;
+ free(ms->drmmode.shadow_fb2);
+ ms->drmmode.shadow_fb2 = NULL;
}
drmmode_uevent_fini(pScrn, &ms->drmmode);
diff --git a/hw/xfree86/drivers/modesetting/drmmode_display.c b/hw/xfree86/drivers/modesetting/drmmode_display.c
index 125a9fb..d86df36 100644
--- a/hw/xfree86/drivers/modesetting/drmmode_display.c
+++ b/hw/xfree86/drivers/modesetting/drmmode_display.c
@@ -1637,6 +1637,19 @@ drmmode_xf86crtc_resize(ScrnInfoPtr scrn, int width, int height)
drmmode->shadow_fb = new_pixels;
}
+ if (drmmode->shadow_enable2) {
+ uint32_t size = scrn->displayWidth * scrn->virtualY * cpp;
+ new_pixels = calloc(1, size);
+ free(drmmode->shadow_fb2);
+ if (new_pixels == NULL) {
+ /* fall back to single-shadow, retry next time we resize */
+ new_pixels = drmmode->shadow_fb;
+ drmmode->shadow_fb2 = NULL;
+ } else {
+ drmmode->shadow_fb2 = new_pixels;
+ }
+ }
+
screen->ModifyPixmapHeader(ppix, width, height, -1, -1,
scrn->displayWidth * cpp, new_pixels);
diff --git a/hw/xfree86/drivers/modesetting/drmmode_display.h b/hw/xfree86/drivers/modesetting/drmmode_display.h
index f0c7a6e..191dc60 100644
--- a/hw/xfree86/drivers/modesetting/drmmode_display.h
+++ b/hw/xfree86/drivers/modesetting/drmmode_display.h
@@ -63,10 +63,12 @@ typedef struct {
Bool glamor;
Bool shadow_enable;
+ Bool shadow_enable2;
/** Is Option "PageFlip" enabled? */
Bool pageflip;
Bool force_24_32;
void *shadow_fb;
+ void *shadow_fb2;
DevPrivateKeyRec pixmapPrivateKeyRec;
--
2.4.3
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