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 "util/u_atomic.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    int pos = 0;
  48    int used = batch->used;
  49    uint8_t *buffer = batch->buffer;
  50
  51    _glapi_set_dispatch(ctx->CurrentServerDispatch);
  52
  53    while (pos < used) {
  54       const struct marshal_cmd_base *cmd =
  55          (const struct marshal_cmd_base *)&buffer[pos];
  56
  57       _mesa_unmarshal_dispatch[cmd->cmd_id](ctx, cmd);
  58       pos += cmd->cmd_size;
  59    }
  60
  61    assert(pos == used);
  62    batch->used = 0;
  63 }
  64
  65 static void
  66 glthread_thread_initialization(void *job, int thread_index)
  67 {
  68    struct gl_context *ctx = (struct gl_context*)job;
  69
  70    ctx->Driver.SetBackgroundContext(ctx, &ctx->GLThread->stats);
  71    _glapi_set_context(ctx);
  72 }
  73
  74 void
  75 _mesa_glthread_init(struct gl_context *ctx)
  76 {
  77    struct glthread_state *glthread = calloc(1, sizeof(*glthread));
  78
  79    if (!glthread)
  80       return;
  81
  82    if (!util_queue_init(&glthread->queue, "gl", MARSHAL_MAX_BATCHES - 2,
  83                         1, 0)) {
  84       free(glthread);
  85       return;
  86    }
  87
  88    ctx->MarshalExec = _mesa_create_marshal_table(ctx);
  89    if (!ctx->MarshalExec) {
  90       util_queue_destroy(&glthread->queue);
  91       free(glthread);
  92       return;
  93    }
  94
  95    for (unsigned i = 0; i < MARSHAL_MAX_BATCHES; i++) {
  96       glthread->batches[i].ctx = ctx;
  97       util_queue_fence_init(&glthread->batches[i].fence);
  98    }
  99
 100    glthread->stats.queue = &glthread->queue;
 101    ctx->CurrentClientDispatch = ctx->MarshalExec;
 102    ctx->GLThread = glthread;
 103
 104    /* Execute the thread initialization function in the thread. */
 105    struct util_queue_fence fence;
 106    util_queue_fence_init(&fence);
 107    util_queue_add_job(&glthread->queue, ctx, &fence,
 108                       glthread_thread_initialization, NULL, 0);
 109    util_queue_fence_wait(&fence);
 110    util_queue_fence_destroy(&fence);
 111 }
 112
 113 void
 114 _mesa_glthread_destroy(struct gl_context *ctx)
 115 {
 116    struct glthread_state *glthread = ctx->GLThread;
 117
 118    if (!glthread)
 119       return;
 120
 121    _mesa_glthread_finish(ctx);
 122    util_queue_destroy(&glthread->queue);
 123
 124    for (unsigned i = 0; i < MARSHAL_MAX_BATCHES; i++)
 125       util_queue_fence_destroy(&glthread->batches[i].fence);
 126
 127    free(glthread);
 128    ctx->GLThread = NULL;
 129
 130    _mesa_glthread_restore_dispatch(ctx, "destroy");
 131 }
 132
 133 void
 134 _mesa_glthread_restore_dispatch(struct gl_context *ctx, const char *func)
 135 {
 136    /* Remove ourselves from the dispatch table except if another ctx/thread
 137     * already installed a new dispatch table.
 138     *
 139     * Typically glxMakeCurrent will bind a new context (install new table) then
 140     * old context might be deleted.
 141     */
 142    if (_glapi_get_dispatch() == ctx->MarshalExec) {
 143        ctx->CurrentClientDispatch = ctx->CurrentServerDispatch;
 144        _glapi_set_dispatch(ctx->CurrentClientDispatch);
 145 #if 0
 146        printf("glthread disabled: %s\n", func);
 147 #endif
 148    }
 149 }
 150
 151 void
 152 _mesa_glthread_flush_batch(struct gl_context *ctx)
 153 {
 154    struct glthread_state *glthread = ctx->GLThread;
 155    if (!glthread)
 156       return;
 157
 158    struct glthread_batch *next = &glthread->batches[glthread->next];
 159    if (!next->used)
 160       return;
 161
 162    /* Debug: execute the batch immediately from this thread.
 163     *
 164     * Note that glthread_unmarshal_batch() changes the dispatch table so we'll
 165     * need to restore it when it returns.
 166     */
 167    if (false) {
 168       glthread_unmarshal_batch(next, 0);
 169       _glapi_set_dispatch(ctx->CurrentClientDispatch);
 170       return;
 171    }
 172
 173    p_atomic_add(&glthread->stats.num_offloaded_items, next->used);
 174
 175    util_queue_add_job(&glthread->queue, next, &next->fence,
 176                       glthread_unmarshal_batch, NULL, 0);
 177    glthread->last = glthread->next;
 178    glthread->next = (glthread->next + 1) % MARSHAL_MAX_BATCHES;
 179 }
 180
 181 /**
 182  * Waits for all pending batches have been unmarshaled.
 183  *
 184  * This can be used by the main thread to synchronize access to the context,
 185  * since the worker thread will be idle after this.
 186  */
 187 void
 188 _mesa_glthread_finish(struct gl_context *ctx)
 189 {
 190    struct glthread_state *glthread = ctx->GLThread;
 191    if (!glthread)
 192       return;
 193
 194    /* If this is called from the worker thread, then we've hit a path that
 195     * might be called from either the main thread or the worker (such as some
 196     * dri interface entrypoints), in which case we don't need to actually
 197     * synchronize against ourself.
 198     */
 199    if (u_thread_is_self(glthread->queue.threads[0]))
 200       return;
 201
 202    struct glthread_batch *last = &glthread->batches[glthread->last];
 203    struct glthread_batch *next = &glthread->batches[glthread->next];
 204    bool synced = false;
 205
 206    if (!util_queue_fence_is_signalled(&last->fence)) {
 207       util_queue_fence_wait(&last->fence);
 208       synced = true;
 209    }
 210
 211    if (next->used) {
 212       p_atomic_add(&glthread->stats.num_direct_items, next->used);
 213
 214       /* Since glthread_unmarshal_batch changes the dispatch to direct,
 215        * restore it after it's done.
 216        */
 217       struct _glapi_table *dispatch = _glapi_get_dispatch();
 218       glthread_unmarshal_batch(next, 0);
 219       _glapi_set_dispatch(dispatch);
 220
 221       /* It's not a sync because we don't enqueue partial batches, but
 222        * it would be a sync if we did. So count it anyway.
 223        */
 224       synced = true;
 225    }
 226
 227    if (synced)
 228       p_atomic_inc(&glthread->stats.num_syncs);
 229 }