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_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    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
  59 static void
  60 glthread_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
  68 void
  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, 0);
 103    util_queue_fence_wait(&fence);
 104    util_queue_fence_destroy(&fence);
 105 }
 106
 107 void
 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, "destroy");
 125 }
 126
 127 void
 128 _mesa_glthread_restore_dispatch(struct gl_context *ctx, const char *func)
 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 #if 0
 140        printf("glthread disabled: %s\n", func);
 141 #endif
 142    }
 143 }
 144
 145 void
 146 _mesa_glthread_flush_batch(struct gl_context *ctx)
 147 {
 148    struct glthread_state *glthread = ctx->GLThread;
 149    if (!glthread)
 150       return;
 151
 152    struct glthread_batch *next = &glthread->batches[glthread->next];
 153    if (!next->used)
 154       return;
 155
 156    /* Debug: execute the batch immediately from this thread.
 157     *
 158     * Note that glthread_unmarshal_batch() changes the dispatch table so we'll
 159     * need to restore it when it returns.
 160     */
 161    if (false) {
 162       glthread_unmarshal_batch(next, 0);
 163       _glapi_set_dispatch(ctx->CurrentClientDispatch);
 164       return;
 165    }
 166
 167    p_atomic_add(&glthread->stats.num_offloaded_items, next->used);
 168
 169    util_queue_add_job(&glthread->queue, next, &next->fence,
 170                       glthread_unmarshal_batch, NULL, 0);
 171    glthread->last = glthread->next;
 172    glthread->next = (glthread->next + 1) % MARSHAL_MAX_BATCHES;
 173 }
 174
 175 /**
 176  * Waits for all pending batches have been unmarshaled.
 177  *
 178  * This can be used by the main thread to synchronize access to the context,
 179  * since the worker thread will be idle after this.
 180  */
 181 void
 182 _mesa_glthread_finish(struct gl_context *ctx)
 183 {
 184    struct glthread_state *glthread = ctx->GLThread;
 185    if (!glthread)
 186       return;
 187
 188    /* If this is called from the worker thread, then we've hit a path that
 189     * might be called from either the main thread or the worker (such as some
 190     * dri interface entrypoints), in which case we don't need to actually
 191     * synchronize against ourself.
 192     */
 193    if (u_thread_is_self(glthread->queue.threads[0]))
 194       return;
 195
 196    struct glthread_batch *last = &glthread->batches[glthread->last];
 197    struct glthread_batch *next = &glthread->batches[glthread->next];
 198    bool synced = false;
 199
 200    if (!util_queue_fence_is_signalled(&last->fence)) {
 201       util_queue_fence_wait(&last->fence);
 202       synced = true;
 203    }
 204
 205    if (next->used) {
 206       p_atomic_add(&glthread->stats.num_direct_items, next->used);
 207
 208       /* Since glthread_unmarshal_batch changes the dispatch to direct,
 209        * restore it after it's done.
 210        */
 211       struct _glapi_table *dispatch = _glapi_get_dispatch();
 212       glthread_unmarshal_batch(next, 0);
 213       _glapi_set_dispatch(dispatch);
 214
 215       /* It's not a sync because we don't enqueue partial batches, but
 216        * it would be a sync if we did. So count it anyway.
 217        */
 218       synced = true;
 219    }
 220
 221    if (synced)
 222       p_atomic_inc(&glthread->stats.num_syncs);
 223 }