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/glthread_marshal.h"
  38 #include "main/hash.h"
  39 #include "util/u_atomic.h"
  40 #include "util/u_thread.h"
  41
  42
  43 static void
  44 glthread_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    int pos = 0;
  49    int used = batch->used;
  50    uint8_t *buffer = batch->buffer;
  51
  52    _glapi_set_dispatch(ctx->CurrentServerDispatch);
  53
  54    while (pos < used) {
  55       const struct marshal_cmd_base *cmd =
  56          (const struct marshal_cmd_base *)&buffer[pos];
  57
  58       _mesa_unmarshal_dispatch[cmd->cmd_id](ctx, cmd);
  59       pos += cmd->cmd_size;
  60    }
  61
  62    assert(pos == used);
  63    batch->used = 0;
  64 }
  65
  66 static void
  67 glthread_thread_initialization(void *job, int thread_index)
  68 {
  69    struct gl_context *ctx = (struct gl_context*)job;
  70
  71    ctx->Driver.SetBackgroundContext(ctx, &ctx->GLThread.stats);
  72    _glapi_set_context(ctx);
  73 }
  74
  75 void
  76 _mesa_glthread_init(struct gl_context *ctx)
  77 {
  78    struct glthread_state *glthread = &ctx->GLThread;
  79
  80    assert(!glthread->enabled);
  81
  82    if (!util_queue_init(&glthread->queue, "gl", MARSHAL_MAX_BATCHES - 2,
  83                         1, 0)) {
  84       return;
  85    }
  86
  87    glthread->VAOs = _mesa_NewHashTable();
  88    if (!glthread->VAOs) {
  89       util_queue_destroy(&glthread->queue);
  90       return;
  91    }
  92
  93    _mesa_glthread_reset_vao(&glthread->DefaultVAO);
  94    glthread->CurrentVAO = &glthread->DefaultVAO;
  95
  96    ctx->MarshalExec = _mesa_create_marshal_table(ctx);
  97    if (!ctx->MarshalExec) {
  98       _mesa_DeleteHashTable(glthread->VAOs);
  99       util_queue_destroy(&glthread->queue);
 100       return;
 101    }
 102
 103    for (unsigned i = 0; i < MARSHAL_MAX_BATCHES; i++) {
 104       glthread->batches[i].ctx = ctx;
 105       util_queue_fence_init(&glthread->batches[i].fence);
 106    }
 107    glthread->next_batch = &glthread->batches[glthread->next];
 108
 109    glthread->enabled = true;
 110    glthread->stats.queue = &glthread->queue;
 111
 112    glthread->SupportsBufferUploads =
 113       ctx->Const.BufferCreateMapUnsynchronizedThreadSafe &&
 114       ctx->Const.AllowMappedBuffersDuringExecution;
 115
 116    /* If the draw start index is non-zero, glthread can upload to offset 0,
 117     * which means the attrib offset has to be -(first * stride).
 118     * So require signed vertex buffer offsets.
 119     */
 120    glthread->SupportsNonVBOUploads = glthread->SupportsBufferUploads &&
 121                                      ctx->Const.VertexBufferOffsetIsInt32;
 122
 123    ctx->CurrentClientDispatch = ctx->MarshalExec;
 124
 125    /* Execute the thread initialization function in the thread. */
 126    struct util_queue_fence fence;
 127    util_queue_fence_init(&fence);
 128    util_queue_add_job(&glthread->queue, ctx, &fence,
 129                       glthread_thread_initialization, NULL, 0);
 130    util_queue_fence_wait(&fence);
 131    util_queue_fence_destroy(&fence);
 132 }
 133
 134 static void
 135 free_vao(GLuint key, void *data, void *userData)
 136 {
 137    free(data);
 138 }
 139
 140 void
 141 _mesa_glthread_destroy(struct gl_context *ctx)
 142 {
 143    struct glthread_state *glthread = &ctx->GLThread;
 144
 145    if (!glthread->enabled)
 146       return;
 147
 148    _mesa_glthread_finish(ctx);
 149    util_queue_destroy(&glthread->queue);
 150
 151    for (unsigned i = 0; i < MARSHAL_MAX_BATCHES; i++)
 152       util_queue_fence_destroy(&glthread->batches[i].fence);
 153
 154    _mesa_HashDeleteAll(glthread->VAOs, free_vao, NULL);
 155    _mesa_DeleteHashTable(glthread->VAOs);
 156
 157    ctx->GLThread.enabled = false;
 158
 159    _mesa_glthread_restore_dispatch(ctx, "destroy");
 160 }
 161
 162 void
 163 _mesa_glthread_restore_dispatch(struct gl_context *ctx, const char *func)
 164 {
 165    /* Remove ourselves from the dispatch table except if another ctx/thread
 166     * already installed a new dispatch table.
 167     *
 168     * Typically glxMakeCurrent will bind a new context (install new table) then
 169     * old context might be deleted.
 170     */
 171    if (_glapi_get_dispatch() == ctx->MarshalExec) {
 172        ctx->CurrentClientDispatch = ctx->CurrentServerDispatch;
 173        _glapi_set_dispatch(ctx->CurrentClientDispatch);
 174 #if 0
 175        printf("glthread disabled: %s\n", func);
 176 #endif
 177    }
 178 }
 179
 180 void
 181 _mesa_glthread_disable(struct gl_context *ctx, const char *func)
 182 {
 183    _mesa_glthread_finish_before(ctx, func);
 184    _mesa_glthread_restore_dispatch(ctx, func);
 185 }
 186
 187 void
 188 _mesa_glthread_flush_batch(struct gl_context *ctx)
 189 {
 190    struct glthread_state *glthread = &ctx->GLThread;
 191    if (!glthread->enabled)
 192       return;
 193
 194    struct glthread_batch *next = glthread->next_batch;
 195    if (!next->used)
 196       return;
 197
 198    /* Debug: execute the batch immediately from this thread.
 199     *
 200     * Note that glthread_unmarshal_batch() changes the dispatch table so we'll
 201     * need to restore it when it returns.
 202     */
 203    if (false) {
 204       glthread_unmarshal_batch(next, 0);
 205       _glapi_set_dispatch(ctx->CurrentClientDispatch);
 206       return;
 207    }
 208
 209    p_atomic_add(&glthread->stats.num_offloaded_items, next->used);
 210
 211    util_queue_add_job(&glthread->queue, next, &next->fence,
 212                       glthread_unmarshal_batch, NULL, 0);
 213    glthread->last = glthread->next;
 214    glthread->next = (glthread->next + 1) % MARSHAL_MAX_BATCHES;
 215    glthread->next_batch = &glthread->batches[glthread->next];
 216 }
 217
 218 /**
 219  * Waits for all pending batches have been unmarshaled.
 220  *
 221  * This can be used by the main thread to synchronize access to the context,
 222  * since the worker thread will be idle after this.
 223  */
 224 void
 225 _mesa_glthread_finish(struct gl_context *ctx)
 226 {
 227    struct glthread_state *glthread = &ctx->GLThread;
 228    if (!glthread->enabled)
 229       return;
 230
 231    /* If this is called from the worker thread, then we've hit a path that
 232     * might be called from either the main thread or the worker (such as some
 233     * dri interface entrypoints), in which case we don't need to actually
 234     * synchronize against ourself.
 235     */
 236    if (u_thread_is_self(glthread->queue.threads[0]))
 237       return;
 238
 239    struct glthread_batch *last = &glthread->batches[glthread->last];
 240    struct glthread_batch *next = glthread->next_batch;
 241    bool synced = false;
 242
 243    if (!util_queue_fence_is_signalled(&last->fence)) {
 244       util_queue_fence_wait(&last->fence);
 245       synced = true;
 246    }
 247
 248    if (next->used) {
 249       p_atomic_add(&glthread->stats.num_direct_items, next->used);
 250
 251       /* Since glthread_unmarshal_batch changes the dispatch to direct,
 252        * restore it after it's done.
 253        */
 254       struct _glapi_table *dispatch = _glapi_get_dispatch();
 255       glthread_unmarshal_batch(next, 0);
 256       _glapi_set_dispatch(dispatch);
 257
 258       /* It's not a sync because we don't enqueue partial batches, but
 259        * it would be a sync if we did. So count it anyway.
 260        */
 261       synced = true;
 262    }
 263
 264    if (synced)
 265       p_atomic_inc(&glthread->stats.num_syncs);
 266 }
 267
 268 void
 269 _mesa_glthread_finish_before(struct gl_context *ctx, const char *func)
 270 {
 271    _mesa_glthread_finish(ctx);
 272
 273    /* Uncomment this if you want to know where glthread syncs. */
 274    /*printf("fallback to sync: %s\n", func);*/
 275 }