vpx/vp9/decoder/vp9_thread.c
Yunqing Wang 903801f1ef vp9 decoder: row-based multi-threaded loopfilter
Implemented parallel loopfiltering, which uses existing tile-
decoding threads. Each thread works on one row, and when that row
is loopfiltered, it moves to next unattended row. To ensure the
correct filtering order, threads are synchronized and one
superblock is filtered only if the superblocks it depends on are
filtered already.

To reduce synchronization overhead and speed up the decoder, we use
nsync > 1 for high resolution.

Performance tests:
1. on desktop:
8-tile 4k video using 8 threads, speedup: 70% - 80%
4-tile HD video using 4 threads, speedup: ~35%
2. on mobile device(Nexus 7):
4-tile 1080p video using 4 threads, speedup: 18% - 25%
4-tile 1080p video using 2 threads, speedup: 10% - 15%

Change-Id: If54b4a11960dd706c22d5ad145ad94156031f36a
2014-01-31 14:44:53 -08:00

142 lines
4.0 KiB
C

// Copyright 2013 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
// -----------------------------------------------------------------------------
//
// Multi-threaded worker
//
// Original source:
// http://git.chromium.org/webm/libwebp.git
// 100644 blob eff8f2a8c20095aade3c292b0e9292dac6cb3587 src/utils/thread.c
#include <assert.h>
#include <string.h> // for memset()
#include "./vp9_thread.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
#if CONFIG_MULTITHREAD
//------------------------------------------------------------------------------
static THREADFN thread_loop(void *ptr) { // thread loop
VP9Worker* const worker = (VP9Worker*)ptr;
int done = 0;
while (!done) {
pthread_mutex_lock(&worker->mutex_);
while (worker->status_ == OK) { // wait in idling mode
pthread_cond_wait(&worker->condition_, &worker->mutex_);
}
if (worker->status_ == WORK) {
vp9_worker_execute(worker);
worker->status_ = OK;
} else if (worker->status_ == NOT_OK) { // finish the worker
done = 1;
}
// signal to the main thread that we're done (for Sync())
pthread_cond_signal(&worker->condition_);
pthread_mutex_unlock(&worker->mutex_);
}
return THREAD_RETURN(NULL); // Thread is finished
}
// main thread state control
static void change_state(VP9Worker* const worker,
VP9WorkerStatus new_status) {
// no-op when attempting to change state on a thread that didn't come up
if (worker->status_ < OK) return;
pthread_mutex_lock(&worker->mutex_);
// wait for the worker to finish
while (worker->status_ != OK) {
pthread_cond_wait(&worker->condition_, &worker->mutex_);
}
// assign new status and release the working thread if needed
if (new_status != OK) {
worker->status_ = new_status;
pthread_cond_signal(&worker->condition_);
}
pthread_mutex_unlock(&worker->mutex_);
}
#endif // CONFIG_MULTITHREAD
//------------------------------------------------------------------------------
void vp9_worker_init(VP9Worker* const worker) {
memset(worker, 0, sizeof(*worker));
worker->status_ = NOT_OK;
}
int vp9_worker_sync(VP9Worker* const worker) {
#if CONFIG_MULTITHREAD
change_state(worker, OK);
#endif
assert(worker->status_ <= OK);
return !worker->had_error;
}
int vp9_worker_reset(VP9Worker* const worker) {
int ok = 1;
worker->had_error = 0;
if (worker->status_ < OK) {
#if CONFIG_MULTITHREAD
if (pthread_mutex_init(&worker->mutex_, NULL) ||
pthread_cond_init(&worker->condition_, NULL)) {
return 0;
}
pthread_mutex_lock(&worker->mutex_);
ok = !pthread_create(&worker->thread_, NULL, thread_loop, worker);
if (ok) worker->status_ = OK;
pthread_mutex_unlock(&worker->mutex_);
#else
worker->status_ = OK;
#endif
} else if (worker->status_ > OK) {
ok = vp9_worker_sync(worker);
}
assert(!ok || (worker->status_ == OK));
return ok;
}
void vp9_worker_execute(VP9Worker* const worker) {
if (worker->hook != NULL) {
worker->had_error |= !worker->hook(worker->data1, worker->data2);
}
}
void vp9_worker_launch(VP9Worker* const worker) {
#if CONFIG_MULTITHREAD
change_state(worker, WORK);
#else
vp9_worker_execute(worker);
#endif
}
void vp9_worker_end(VP9Worker* const worker) {
if (worker->status_ >= OK) {
#if CONFIG_MULTITHREAD
change_state(worker, NOT_OK);
pthread_join(worker->thread_, NULL);
pthread_mutex_destroy(&worker->mutex_);
pthread_cond_destroy(&worker->condition_);
#else
worker->status_ = NOT_OK;
#endif
}
assert(worker->status_ == NOT_OK);
}
//------------------------------------------------------------------------------
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif