Have separate FBOs per resolution and format.
authorSteinar H. Gunderson <sgunderson@bigfoot.com>
Fri, 21 Mar 2014 23:29:21 +0000 (00:29 +0100)
committerSteinar H. Gunderson <sgunderson@bigfoot.com>
Fri, 21 Mar 2014 23:29:21 +0000 (00:29 +0100)
Seemingly this _also_ costs on NVidia; the demo app is down 0.9 ms/frame or so.
This rapidly started approaching complexity worthy of the ResourcePool,
so I moved the functionality in there even though it's not context-shareable.

effect_chain.cpp
effect_chain.h
resource_pool.cpp
resource_pool.h

index b6f2a5b..c3e1fba 100644 (file)
@@ -68,11 +68,6 @@ EffectChain::~EffectChain()
        if (owns_resource_pool) {
                delete resource_pool;
        }
-       for (map<void *, GLuint>::const_iterator fbo_it = fbos.begin();
-            fbo_it != fbos.end(); ++fbo_it) {
-               glDeleteFramebuffers(1, &fbo_it->second);
-               check_error();
-       }
 }
 
 Input *EffectChain::add_input(Input *input)
@@ -1459,18 +1454,6 @@ void EffectChain::render_to_fbo(GLuint dest_fbo, unsigned width, unsigned height
        glDepthMask(GL_FALSE);
        check_error();
 
-       if (phases.size() > 1) {
-               if (fbos.count(context) == 0) {
-                       glGenFramebuffers(1, &fbo);
-                       check_error();
-                       fbos.insert(make_pair(context, fbo));
-               } else {
-                       fbo = fbos[context];
-               }
-               glBindFramebuffer(GL_FRAMEBUFFER, fbo);
-               check_error();
-       }
-
        set<Phase *> generated_mipmaps;
 
        // We choose the simplest option of having one texture per output,
@@ -1485,7 +1468,7 @@ void EffectChain::render_to_fbo(GLuint dest_fbo, unsigned width, unsigned height
                if (phase_num != phases.size() - 1) {
                        find_output_size(phase);
 
-                       GLuint tex_num = resource_pool->create_2d_texture(GL_RGBA16F_ARB, phase->output_width, phase->output_height);
+                       GLuint tex_num = resource_pool->create_2d_texture(GL_RGBA16F, phase->output_width, phase->output_height);
                        output_textures.insert(make_pair(phase, tex_num));
                }
 
@@ -1536,6 +1519,9 @@ void EffectChain::render_to_fbo(GLuint dest_fbo, unsigned width, unsigned height
                                CHECK(dither_effect->set_int("output_height", height));
                        }
                } else {
+                       fbo = resource_pool->create_fbo(context, GL_RGBA16F, phase->output_width, phase->output_height);
+                       glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+                       check_error();
                        glFramebufferTexture2D(
                                GL_FRAMEBUFFER,
                                GL_COLOR_ATTACHMENT0,
@@ -1573,6 +1559,9 @@ void EffectChain::render_to_fbo(GLuint dest_fbo, unsigned width, unsigned height
                        Node *node = phase->effects[i];
                        node->effect->clear_gl_state();
                }
+               if (phase_num != phases.size() - 1) {
+                       resource_pool->release_fbo(fbo);
+               }
        }
 
        for (map<Phase *, GLuint>::const_iterator texture_it = output_textures.begin();
index 9051195..6ce2332 100644 (file)
@@ -287,7 +287,6 @@ private:
        std::map<Effect *, Node *> node_map;
        Effect *dither_effect;
 
-       std::map<void *, GLuint> fbos;  // One for each OpenGL context.
        std::vector<Input *> inputs;  // Also contained in nodes.
        std::vector<Phase *> phases;
 
index 72b3095..b6f6a31 100644 (file)
@@ -17,10 +17,13 @@ using namespace std;
 namespace movit {
 
 ResourcePool::ResourcePool(size_t program_freelist_max_length,
-                           size_t texture_freelist_max_bytes)
+                           size_t texture_freelist_max_bytes,
+                           size_t fbo_freelist_max_length)
        : program_freelist_max_length(program_freelist_max_length),
          texture_freelist_max_bytes(texture_freelist_max_bytes),
-         texture_freelist_bytes(0) {
+         fbo_freelist_max_length(fbo_freelist_max_length),
+         texture_freelist_bytes(0)
+{
        pthread_mutex_init(&lock, NULL);
 }
 
@@ -48,6 +51,17 @@ ResourcePool::~ResourcePool()
        }
        assert(texture_formats.empty());
        assert(texture_freelist_bytes == 0);
+
+       for (list<GLuint>::const_iterator freelist_it = fbo_freelist.begin();
+            freelist_it != fbo_freelist.end();
+            ++freelist_it) {
+               GLuint free_fbo_num = *freelist_it;
+               assert(fbo_formats.count(free_fbo_num) != 0);
+               fbo_formats.erase(free_fbo_num);
+               glDeleteFramebuffers(1, &free_fbo_num);
+               check_error();
+       }
+       assert(fbo_formats.empty());
 }
 
 void ResourcePool::delete_program(GLuint glsl_program_num)
@@ -238,6 +252,60 @@ void ResourcePool::release_2d_texture(GLuint texture_num)
        pthread_mutex_unlock(&lock);
 }
 
+GLuint ResourcePool::create_fbo(void *context, GLint internal_format, GLsizei width, GLsizei height)
+{
+       pthread_mutex_lock(&lock);
+       // See if there's an FBO on the freelist we can use.
+       for (list<GLuint>::iterator freelist_it = fbo_freelist.begin();
+            freelist_it != fbo_freelist.end();
+            ++freelist_it) {
+               GLuint fbo_num = *freelist_it;
+               map<GLuint, FBO>::const_iterator format_it = fbo_formats.find(fbo_num);
+               assert(format_it != fbo_formats.end());
+               if (format_it->second.context == context &&
+                   format_it->second.internal_format == internal_format &&
+                   format_it->second.width == width &&
+                   format_it->second.height == height) {
+                       fbo_freelist.erase(freelist_it);
+                       pthread_mutex_unlock(&lock);
+                       return fbo_num;
+               }
+       }
+
+       // Create a new one.
+       GLuint fbo_num;
+       glGenFramebuffers(1, &fbo_num);
+       check_error();
+
+       FBO fbo_format;
+       fbo_format.context = context;
+       fbo_format.internal_format = internal_format;
+       fbo_format.width = width;
+       fbo_format.height = height;
+       assert(fbo_formats.count(fbo_num) == 0);
+       fbo_formats.insert(make_pair(fbo_num, fbo_format));
+
+       pthread_mutex_unlock(&lock);
+       return fbo_num;
+}
+
+void ResourcePool::release_fbo(GLuint fbo_num)
+{
+       pthread_mutex_lock(&lock);
+       fbo_freelist.push_front(fbo_num);
+       assert(fbo_formats.count(fbo_num) != 0);
+
+       while (fbo_freelist.size() > fbo_freelist_max_length) {
+               GLuint free_fbo_num = fbo_freelist.front();
+               fbo_freelist.pop_front();
+               assert(fbo_formats.count(free_fbo_num) != 0);
+               fbo_formats.erase(free_fbo_num);
+               glDeleteFramebuffers(1, &free_fbo_num);
+               check_error();
+       }
+       pthread_mutex_unlock(&lock);
+}
+
 size_t ResourcePool::estimate_texture_size(const Texture2D &texture_format)
 {
        size_t bytes_per_pixel;
index 14c75e2..86d0059 100644 (file)
@@ -40,7 +40,8 @@ public:
        // This means you should be prepared for actual memory usage of the freelist being
        // twice this estimate or more.
        ResourcePool(size_t program_freelist_max_length = 100,
-                    size_t texture_freelist_max_bytes = 100 << 20);  // 100 MB.
+                    size_t texture_freelist_max_bytes = 100 << 20,  // 100 MB.
+                    size_t fbo_freelist_max_length = 100);
        ~ResourcePool();
 
        // All remaining functions are intended for calls from EffectChain only.
@@ -59,6 +60,19 @@ public:
        GLuint create_2d_texture(GLint internal_format, GLsizei width, GLsizei height);
        void release_2d_texture(GLuint texture_num);
 
+       // Allocate an FBO used for the given internal format and dimensions,
+       // or fetch a previous used if possible. Keeps ownership of the FBO;
+       // you must call release_fbo() of deleting it when you no longer want it.
+       // You can get an appropriate context pointer from get_gl_context_identifier().
+       //
+       // NOTE: In principle, the FBO doesn't have a resolution or pixel format;
+       // you can bind almost whatever texture you want to it. However, changing
+       // resolution or pixel formats can have an adverse effect on performance,
+       // in particular on NVidia cards. Also, keep in mind that FBOs are not
+       // shareable across contexts.
+       GLuint create_fbo(void *context, GLint internal_format, GLsizei width, GLsizei height);
+       void release_fbo(GLuint fbo_num);
+
 private:
        // Delete the given program and both its shaders.
        void delete_program(GLuint program_num);
@@ -66,7 +80,7 @@ private:
        // Protects all the other elements in the class.
        pthread_mutex_t lock;
 
-       size_t program_freelist_max_length, texture_freelist_max_bytes;
+       size_t program_freelist_max_length, texture_freelist_max_bytes, fbo_freelist_max_length;
                
        // A mapping from vertex/fragment shader source strings to compiled program number.
        std::map<std::pair<std::string, std::string>, GLuint> programs;
@@ -102,6 +116,22 @@ private:
        std::list<GLuint> texture_freelist;
        size_t texture_freelist_bytes;
 
+       struct FBO {
+               void *context;
+               GLint internal_format;
+               GLsizei width, height;
+       };
+
+       // A mapping from FBO number to format details. This is filled if the
+       // FBO is given out to a client or on the freelist, but not if it is
+       // deleted from the freelist.
+       std::map<GLuint, FBO> fbo_formats;
+
+       // A list of all FBOs that are release but not freed (most recently freed
+       // first). Once this reaches <fbo_freelist_max_length>, the last element
+       // will be deleted.
+       std::list<GLuint> fbo_freelist;
+
        // See the caveats at the constructor.
        static size_t estimate_texture_size(const Texture2D &texture_format);
 };