src/mesa/main/glthread.c

   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_thread.h"
  40
  41
  42 static void
  43 glthread_unmarshal_batch(void *job, int thread_index)
  44 {
  45    struct glthread_batch *batch = (struct glthread_batch*)job;
  46    struct gl_context *ctx = batch->ctx;
  47    size_t pos = 0;
  48
  49    _glapi_set_dispatch(ctx->CurrentServerDispatch);
  50
  51    while (pos < batch->used)
  52       pos += _mesa_unmarshal_dispatch_cmd(ctx, &batch->buffer[pos]);
  53
  54    assert(pos == batch->used);
  55    batch->used = 0;
  56 }
  57
  58 static void
  59 glthread_thread_initialization(void *job, int thread_index)
  60 {
  61    struct gl_context *ctx = (struct gl_context*)job;
  62
  63    ctx->Driver.SetBackgroundContext(ctx);
  64    _glapi_set_context(ctx);
  65 }
  66
  67 void
  68 _mesa_glthread_init(struct gl_context *ctx)
  69 {
  70    struct glthread_state *glthread = calloc(1, sizeof(*glthread));
  71
  72    if (!glthread)
  73       return;
  74
  75    if (!util_queue_init(&glthread->queue, "glthread", MARSHAL_MAX_BATCHES - 2,
  76                         1, 0)) {
  77       free(glthread);
  78       return;
  79    }
  80
  81    ctx->MarshalExec = _mesa_create_marshal_table(ctx);
  82    if (!ctx->MarshalExec) {
  83       util_queue_destroy(&glthread->queue);
  84       free(glthread);
  85       return;
  86    }
  87
  88    for (unsigned i = 0; i < MARSHAL_MAX_BATCHES; i++) {
  89       glthread->batches[i].ctx = ctx;
  90       util_queue_fence_init(&glthread->batches[i].fence);
  91    }
  92
  93    ctx->CurrentClientDispatch = ctx->MarshalExec;
  94    ctx->GLThread = glthread;
  95
  96    /* Execute the thread initialization function in the thread. */
  97    struct util_queue_fence fence;
  98    util_queue_fence_init(&fence);
  99    util_queue_add_job(&glthread->queue, ctx, &fence,
 100                       glthread_thread_initialization, NULL);
 101    util_queue_fence_wait(&fence);
 102    util_queue_fence_destroy(&fence);
 103 }
 104
 105 void
 106 _mesa_glthread_destroy(struct gl_context *ctx)
 107 {
 108    struct glthread_state *glthread = ctx->GLThread;
 109
 110    if (!glthread)
 111       return;
 112
 113    _mesa_glthread_finish(ctx);
 114    util_queue_destroy(&glthread->queue);
 115
 116    for (unsigned i = 0; i < MARSHAL_MAX_BATCHES; i++)
 117       util_queue_fence_destroy(&glthread->batches[i].fence);
 118
 119    free(glthread);
 120    ctx->GLThread = NULL;
 121
 122    _mesa_glthread_restore_dispatch(ctx);
 123 }
 124
 125 void
 126 _mesa_glthread_restore_dispatch(struct gl_context *ctx)
 127 {
 128    /* Remove ourselves from the dispatch table except if another ctx/thread
 129     * already installed a new dispatch table.
 130     *
 131     * Typically glxMakeCurrent will bind a new context (install new table) then
 132     * old context might be deleted.
 133     */
 134    if (_glapi_get_dispatch() == ctx->MarshalExec) {
 135        ctx->CurrentClientDispatch = ctx->CurrentServerDispatch;
 136        _glapi_set_dispatch(ctx->CurrentClientDispatch);
 137    }
 138 }
 139
 140 void
 141 _mesa_glthread_flush_batch(struct gl_context *ctx)
 142 {
 143    struct glthread_state *glthread = ctx->GLThread;
 144    if (!glthread)
 145       return;
 146
 147    struct glthread_batch *next = &glthread->batches[glthread->next];
 148    if (!next->used)
 149       return;
 150
 151    /* Debug: execute the batch immediately from this thread.
 152     *
 153     * Note that glthread_unmarshal_batch() changes the dispatch table so we'll
 154     * need to restore it when it returns.
 155     */
 156    if (false) {
 157       glthread_unmarshal_batch(next, 0);
 158       _glapi_set_dispatch(ctx->CurrentClientDispatch);
 159       return;
 160    }
 161
 162    util_queue_add_job(&glthread->queue, next, &next->fence,
 163                       glthread_unmarshal_batch, NULL);
 164    glthread->last = glthread->next;
 165    glthread->next = (glthread->next + 1) % MARSHAL_MAX_BATCHES;
 166 }
 167
 168 /**
 169  * Waits for all pending batches have been unmarshaled.
 170  *
 171  * This can be used by the main thread to synchronize access to the context,
 172  * since the worker thread will be idle after this.
 173  */
 174 void
 175 _mesa_glthread_finish(struct gl_context *ctx)
 176 {
 177    struct glthread_state *glthread = ctx->GLThread;
 178    if (!glthread)
 179       return;
 180
 181    /* If this is called from the worker thread, then we've hit a path that
 182     * might be called from either the main thread or the worker (such as some
 183     * dri interface entrypoints), in which case we don't need to actually
 184     * synchronize against ourself.
 185     */
 186    if (u_thread_is_self(glthread->queue.threads[0]))
 187       return;
 188
 189    struct glthread_batch *last = &glthread->batches[glthread->last];
 190    struct glthread_batch *next = &glthread->batches[glthread->next];
 191
 192    if (!util_queue_fence_is_signalled(&last->fence))
 193       util_queue_fence_wait(&last->fence);
 194
 195    if (next->used) {
 196       /* Since glthread_unmarshal_batch changes the dispatch to direct,
 197        * restore it after it's done.
 198        */
 199       struct _glapi_table *dispatch = _glapi_get_dispatch();
 200       glthread_unmarshal_batch(next, 0);
 201       _glapi_set_dispatch(dispatch);
 202    }
 203 }