glthread.c revision 01e04c3f 
1/*
2 * Copyright © 2012 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21 * IN THE SOFTWARE.
22 */
23
24/** @file glthread.c
25 *
26 * Support functions for the glthread feature of Mesa.
27 *
28 * In multicore systems, many applications end up CPU-bound with about half
29 * their time spent inside their rendering thread and half inside Mesa.  To
30 * alleviate this, we put a shim layer in Mesa at the GL dispatch level that
31 * quickly logs the GL commands to a buffer to be processed by a worker
32 * thread.
33 */
34
35#include "main/mtypes.h"
36#include "main/glthread.h"
37#include "main/marshal.h"
38#include "main/marshal_generated.h"
39#include "util/u_atomic.h"
40#include "util/u_thread.h"
41
42
43static void
44glthread_unmarshal_batch(void *job, int thread_index)
45{
46   struct glthread_batch *batch = (struct glthread_batch*)job;
47   struct gl_context *ctx = batch->ctx;
48   size_t pos = 0;
49
50   _glapi_set_dispatch(ctx->CurrentServerDispatch);
51
52   while (pos < batch->used)
53      pos += _mesa_unmarshal_dispatch_cmd(ctx, &batch->buffer[pos]);
54
55   assert(pos == batch->used);
56   batch->used = 0;
57}
58
59static void
60glthread_thread_initialization(void *job, int thread_index)
61{
62   struct gl_context *ctx = (struct gl_context*)job;
63
64   ctx->Driver.SetBackgroundContext(ctx, &ctx->GLThread->stats);
65   _glapi_set_context(ctx);
66}
67
68void
69_mesa_glthread_init(struct gl_context *ctx)
70{
71   struct glthread_state *glthread = calloc(1, sizeof(*glthread));
72
73   if (!glthread)
74      return;
75
76   if (!util_queue_init(&glthread->queue, "gl", MARSHAL_MAX_BATCHES - 2,
77                        1, 0)) {
78      free(glthread);
79      return;
80   }
81
82   ctx->MarshalExec = _mesa_create_marshal_table(ctx);
83   if (!ctx->MarshalExec) {
84      util_queue_destroy(&glthread->queue);
85      free(glthread);
86      return;
87   }
88
89   for (unsigned i = 0; i < MARSHAL_MAX_BATCHES; i++) {
90      glthread->batches[i].ctx = ctx;
91      util_queue_fence_init(&glthread->batches[i].fence);
92   }
93
94   glthread->stats.queue = &glthread->queue;
95   ctx->CurrentClientDispatch = ctx->MarshalExec;
96   ctx->GLThread = glthread;
97
98   /* Execute the thread initialization function in the thread. */
99   struct util_queue_fence fence;
100   util_queue_fence_init(&fence);
101   util_queue_add_job(&glthread->queue, ctx, &fence,
102                      glthread_thread_initialization, NULL);
103   util_queue_fence_wait(&fence);
104   util_queue_fence_destroy(&fence);
105}
106
107void
108_mesa_glthread_destroy(struct gl_context *ctx)
109{
110   struct glthread_state *glthread = ctx->GLThread;
111
112   if (!glthread)
113      return;
114
115   _mesa_glthread_finish(ctx);
116   util_queue_destroy(&glthread->queue);
117
118   for (unsigned i = 0; i < MARSHAL_MAX_BATCHES; i++)
119      util_queue_fence_destroy(&glthread->batches[i].fence);
120
121   free(glthread);
122   ctx->GLThread = NULL;
123
124   _mesa_glthread_restore_dispatch(ctx);
125}
126
127void
128_mesa_glthread_restore_dispatch(struct gl_context *ctx)
129{
130   /* Remove ourselves from the dispatch table except if another ctx/thread
131    * already installed a new dispatch table.
132    *
133    * Typically glxMakeCurrent will bind a new context (install new table) then
134    * old context might be deleted.
135    */
136   if (_glapi_get_dispatch() == ctx->MarshalExec) {
137       ctx->CurrentClientDispatch = ctx->CurrentServerDispatch;
138       _glapi_set_dispatch(ctx->CurrentClientDispatch);
139   }
140}
141
142void
143_mesa_glthread_flush_batch(struct gl_context *ctx)
144{
145   struct glthread_state *glthread = ctx->GLThread;
146   if (!glthread)
147      return;
148
149   struct glthread_batch *next = &glthread->batches[glthread->next];
150   if (!next->used)
151      return;
152
153   /* Debug: execute the batch immediately from this thread.
154    *
155    * Note that glthread_unmarshal_batch() changes the dispatch table so we'll
156    * need to restore it when it returns.
157    */
158   if (false) {
159      glthread_unmarshal_batch(next, 0);
160      _glapi_set_dispatch(ctx->CurrentClientDispatch);
161      return;
162   }
163
164   p_atomic_add(&glthread->stats.num_offloaded_items, next->used);
165
166   util_queue_add_job(&glthread->queue, next, &next->fence,
167                      glthread_unmarshal_batch, NULL);
168   glthread->last = glthread->next;
169   glthread->next = (glthread->next + 1) % MARSHAL_MAX_BATCHES;
170}
171
172/**
173 * Waits for all pending batches have been unmarshaled.
174 *
175 * This can be used by the main thread to synchronize access to the context,
176 * since the worker thread will be idle after this.
177 */
178void
179_mesa_glthread_finish(struct gl_context *ctx)
180{
181   struct glthread_state *glthread = ctx->GLThread;
182   if (!glthread)
183      return;
184
185   /* If this is called from the worker thread, then we've hit a path that
186    * might be called from either the main thread or the worker (such as some
187    * dri interface entrypoints), in which case we don't need to actually
188    * synchronize against ourself.
189    */
190   if (u_thread_is_self(glthread->queue.threads[0]))
191      return;
192
193   struct glthread_batch *last = &glthread->batches[glthread->last];
194   struct glthread_batch *next = &glthread->batches[glthread->next];
195   bool synced = false;
196
197   if (!util_queue_fence_is_signalled(&last->fence)) {
198      util_queue_fence_wait(&last->fence);
199      synced = true;
200   }
201
202   if (next->used) {
203      p_atomic_add(&glthread->stats.num_direct_items, next->used);
204
205      /* Since glthread_unmarshal_batch changes the dispatch to direct,
206       * restore it after it's done.
207       */
208      struct _glapi_table *dispatch = _glapi_get_dispatch();
209      glthread_unmarshal_batch(next, 0);
210      _glapi_set_dispatch(dispatch);
211
212      /* It's not a sync because we don't enqueue partial batches, but
213       * it would be a sync if we did. So count it anyway.
214       */
215      synced = true;
216   }
217
218   if (synced)
219      p_atomic_inc(&glthread->stats.num_syncs);
220}
221