Mesa (master): ilo: tidy up choose_transfer_method()
Chia-I Wu
olv at kemper.freedesktop.org
Mon Jul 28 14:58:44 UTC 2014
Module: Mesa
Branch: master
Commit: 2f4bed040574494f7d64b275efc6c5fd635710af
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=2f4bed040574494f7d64b275efc6c5fd635710af
Author: Chia-I Wu <olvaffe at gmail.com>
Date: Sat Jul 26 01:10:21 2014 +0800
ilo: tidy up choose_transfer_method()
Add a bunch of helper functions and a big comment for
choose_transfer_method(). This also fixes handling of
PIPE_TRANSFER_MAP_DIRECTLY to not ignore tiling.
---
src/gallium/drivers/ilo/ilo_transfer.c | 248 +++++++++++++++++++++-----------
1 file changed, 164 insertions(+), 84 deletions(-)
diff --git a/src/gallium/drivers/ilo/ilo_transfer.c b/src/gallium/drivers/ilo/ilo_transfer.c
index 906c201..7645a25 100644
--- a/src/gallium/drivers/ilo/ilo_transfer.c
+++ b/src/gallium/drivers/ilo/ilo_transfer.c
@@ -36,6 +36,159 @@
#include "ilo_state.h"
#include "ilo_transfer.h"
+/*
+ * For buffers that are not busy, we want to map/unmap them directly. For
+ * those that are busy, we have to worry about synchronization. We could wait
+ * for GPU to finish, but there are cases where we could avoid waiting.
+ *
+ * - When PIPE_TRANSFER_DISCARD_WHOLE_RESOURCE is set, the contents of the
+ * buffer can be discarded. We can replace the backing bo by a new one of
+ * the same size (renaming).
+ * - When PIPE_TRANSFER_DISCARD_RANGE is set, the contents of the mapped
+ * range can be discarded. We can allocate and map a staging bo on
+ * mapping, and (pipelined-)copy it over to the real bo on unmapping.
+ * - When PIPE_TRANSFER_FLUSH_EXPLICIT is set, there is no reading and only
+ * flushed regions need to be written. We can still allocate and map a
+ * staging bo, but should copy only the flushed regions over.
+ *
+ * However, there are other flags to consider.
+ *
+ * - When PIPE_TRANSFER_UNSYNCHRONIZED is set, we do not need to worry about
+ * synchronization at all on mapping.
+ * - When PIPE_TRANSFER_MAP_DIRECTLY is set, no staging area is allowed.
+ * - When PIPE_TRANSFER_DONTBLOCK is set, we should fail if we have to block.
+ *
+ * These also apply to textures, except that we may additionally need to do
+ * format conversion or tiling/untiling.
+ */
+
+/**
+ * Return a transfer method suitable for the usage. The returned method will
+ * correctly block when the resource is busy.
+ */
+static bool
+resource_get_transfer_method(struct pipe_resource *res, unsigned usage,
+ enum ilo_transfer_map_method *method)
+{
+ const struct ilo_screen *is = ilo_screen(res->screen);
+ enum ilo_transfer_map_method m;
+ bool tiled;
+
+ if (res->target == PIPE_BUFFER) {
+ tiled = false;
+ }
+ else {
+ struct ilo_texture *tex = ilo_texture(res);
+ bool need_convert = true;
+
+ /* we may need to convert on the fly */
+ if (tex->separate_s8 || tex->bo_format == PIPE_FORMAT_S8_UINT)
+ m = ILO_TRANSFER_MAP_SW_ZS;
+ else if (tex->bo_format != tex->base.format)
+ m = ILO_TRANSFER_MAP_SW_CONVERT;
+ else
+ need_convert = false;
+
+ if (need_convert) {
+ if (usage & PIPE_TRANSFER_MAP_DIRECTLY)
+ return false;
+
+ *method = m;
+ return true;
+ }
+
+ tiled = (tex->tiling != INTEL_TILING_NONE);
+ }
+
+ if (tiled)
+ m = ILO_TRANSFER_MAP_GTT; /* to have a linear view */
+ else if (is->dev.has_llc)
+ m = ILO_TRANSFER_MAP_CPU; /* fast and mostly coherent */
+ else if (usage & PIPE_TRANSFER_READ)
+ m = ILO_TRANSFER_MAP_CPU; /* gtt read is too slow */
+ else
+ m = ILO_TRANSFER_MAP_GTT;
+
+ *method = m;
+
+ return true;
+}
+
+/**
+ * Return the bo of the resource.
+ */
+static struct intel_bo *
+resource_get_bo(struct pipe_resource *res)
+{
+ return (res->target == PIPE_BUFFER) ?
+ ilo_buffer(res)->bo : ilo_texture(res)->bo;
+}
+
+/**
+ * Rename the bo of the resource.
+ */
+static bool
+resource_rename_bo(struct pipe_resource *res)
+{
+ return (res->target == PIPE_BUFFER) ?
+ ilo_buffer_rename_bo(ilo_buffer(res)) :
+ ilo_texture_rename_bo(ilo_texture(res));
+}
+
+/**
+ * Return true if usage allows the use of staging bo to avoid blocking.
+ */
+static bool
+usage_allows_staging_bo(unsigned usage)
+{
+ /* do we know how to write the data back to the resource? */
+ const unsigned can_writeback = (PIPE_TRANSFER_DISCARD_WHOLE_RESOURCE |
+ PIPE_TRANSFER_DISCARD_RANGE |
+ PIPE_TRANSFER_FLUSH_EXPLICIT);
+ const unsigned reasons_against = (PIPE_TRANSFER_READ |
+ PIPE_TRANSFER_MAP_DIRECTLY);
+
+ return (usage & can_writeback) && !(usage & reasons_against);
+}
+
+/**
+ * Use an alternative transfer method or rename the resource to unblock an
+ * otherwise blocking transfer.
+ */
+static bool
+xfer_unblock(struct ilo_transfer *xfer, bool *resource_renamed)
+{
+ struct pipe_resource *res = xfer->base.resource;
+ bool unblocked = false, renamed = false;
+
+ switch (xfer->method) {
+ case ILO_TRANSFER_MAP_CPU:
+ case ILO_TRANSFER_MAP_GTT:
+ if (xfer->base.usage & PIPE_TRANSFER_UNSYNCHRONIZED) {
+ xfer->method = ILO_TRANSFER_MAP_UNSYNC;
+ unblocked = true;
+ }
+ else if ((xfer->base.usage & PIPE_TRANSFER_DISCARD_WHOLE_RESOURCE) &&
+ resource_rename_bo(res)) {
+ renamed = true;
+ unblocked = true;
+ }
+ else if (usage_allows_staging_bo(xfer->base.usage)) {
+ /* TODO */
+ }
+ break;
+ case ILO_TRANSFER_MAP_UNSYNC:
+ unblocked = true;
+ break;
+ default:
+ break;
+ }
+
+ *resource_renamed = renamed;
+
+ return unblocked;
+}
+
static bool
is_bo_busy(struct ilo_context *ilo, struct intel_bo *bo, bool *need_flush)
{
@@ -83,99 +236,26 @@ static bool
choose_transfer_method(struct ilo_context *ilo, struct ilo_transfer *xfer)
{
struct pipe_resource *res = xfer->base.resource;
- const unsigned usage = xfer->base.usage;
- /* prefer map() when there is the last-level cache */
- const bool prefer_cpu =
- (ilo->dev->has_llc || (usage & PIPE_TRANSFER_READ));
- struct ilo_texture *tex;
- struct ilo_buffer *buf;
- struct intel_bo *bo;
- bool tiled, need_flush;
-
- if (res->target == PIPE_BUFFER) {
- tex = NULL;
-
- buf = ilo_buffer(res);
- bo = buf->bo;
- tiled = false;
- }
- else {
- buf = NULL;
-
- tex = ilo_texture(res);
- bo = tex->bo;
- tiled = (tex->tiling != INTEL_TILING_NONE);
- }
+ bool need_flush;
- /* choose between mapping through CPU or GTT */
- if (usage & PIPE_TRANSFER_MAP_DIRECTLY) {
- /* we do not want fencing */
- if (tiled || prefer_cpu)
- xfer->method = ILO_TRANSFER_MAP_CPU;
- else
- xfer->method = ILO_TRANSFER_MAP_GTT;
- }
- else {
- if (!tiled && prefer_cpu)
- xfer->method = ILO_TRANSFER_MAP_CPU;
- else
- xfer->method = ILO_TRANSFER_MAP_GTT;
- }
+ if (!resource_get_transfer_method(res, xfer->base.usage, &xfer->method))
+ return false;
- /* see if we can avoid stalling */
- if (is_bo_busy(ilo, bo, &need_flush)) {
- bool will_stall = true;
+ /* see if we can avoid blocking */
+ if (is_bo_busy(ilo, resource_get_bo(res), &need_flush)) {
+ bool resource_renamed;
- if (usage & PIPE_TRANSFER_MAP_DIRECTLY) {
- /* nothing we can do */
- }
- else if (usage & PIPE_TRANSFER_UNSYNCHRONIZED) {
- /* unsynchronized gtt mapping does not stall */
- xfer->method = ILO_TRANSFER_MAP_UNSYNC;
- will_stall = false;
- }
- else if (usage & PIPE_TRANSFER_DISCARD_WHOLE_RESOURCE) {
- /* discard old bo and allocate a new one for mapping */
- if ((tex && ilo_texture_rename_bo(tex)) ||
- (buf && ilo_buffer_rename_bo(buf))) {
- ilo_mark_states_with_resource_dirty(ilo, res);
- will_stall = false;
- }
- }
- else if (usage & PIPE_TRANSFER_FLUSH_EXPLICIT) {
- /*
- * We could allocate and return a system buffer here. When a region of
- * the buffer is explicitly flushed, we pwrite() the region to a
- * temporary bo and emit pipelined copy blit.
- *
- * For now, do nothing.
- */
- }
- else if (usage & PIPE_TRANSFER_DISCARD_RANGE) {
- /*
- * We could allocate a temporary bo for mapping, and emit pipelined copy
- * blit upon unmapping.
- *
- * For now, do nothing.
- */
- }
-
- if (will_stall) {
- if (usage & PIPE_TRANSFER_DONTBLOCK)
+ if (!xfer_unblock(xfer, &resource_renamed)) {
+ if (xfer->base.usage & PIPE_TRANSFER_DONTBLOCK)
return false;
- /* flush to make bo busy (so that map() stalls as it should be) */
+ /* flush to make bo really busy so that map() correctly blocks */
if (need_flush)
ilo_cp_flush(ilo->cp, "syncing for transfers");
}
- }
- if (tex && !(usage & PIPE_TRANSFER_MAP_DIRECTLY)) {
- if (tex->separate_s8 || tex->bo_format == PIPE_FORMAT_S8_UINT)
- xfer->method = ILO_TRANSFER_MAP_SW_ZS;
- /* need to convert on-the-fly */
- else if (tex->bo_format != tex->base.format)
- xfer->method = ILO_TRANSFER_MAP_SW_CONVERT;
+ if (resource_renamed)
+ ilo_mark_states_with_resource_dirty(ilo, res);
}
return true;
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