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shm: Allocate shm buffers through new wl_shm_pool interface

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There's a big cost to setting up and tearing down a mmap and faulting in
the pages to back it.  For cases where we're continuously reallocating
shm wl_buffers (resizing a surface, typically) it is a big performance
improvement to be able to reuse a mmap area.  This change makes the shm
buffer allocation a two step process: first allocate a wl_shm_pool, then
allocate a buffer from the pool.  The wl_shm_pool encapsulate the shared
memory pool, and lets clients allocate wl_buffers backed by chunks of that
memory.  Buffers are allocated at an offset into the pool, so it's possible
to create multiple buffers from one pool, for example for icons or cursor
images.
This commit is contained in:
Kristian Høgsberg 2012-04-03 12:08:50 -04:00
parent 68cf7a1a42
commit aa777e5b10
2 changed files with 156 additions and 63 deletions
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158
src/wayland-shm.c
View file

@ -33,21 +33,40 @@
#include "wayland-server.h"
struct wl_shm_pool {
struct wl_resource resource;
int refcount;
char *data;
int size;
};
struct wl_shm_buffer {
struct wl_buffer buffer;
int32_t stride;
uint32_t format;
void *data;
struct wl_shm_pool *pool;
};
static void
shm_pool_unref(struct wl_shm_pool *pool)
{
pool->refcount--;
if (pool->refcount)
return;
munmap(pool->data, pool->size);
free(pool);
}
static void
destroy_buffer(struct wl_resource *resource)
{
struct wl_shm_buffer *buffer =
container_of(resource, struct wl_shm_buffer, buffer.resource);
munmap(buffer->data, buffer->stride * buffer->buffer.height);
if (buffer->pool)
shm_pool_unref(buffer->pool);
free(buffer);
}
@ -61,43 +80,14 @@ static const struct wl_buffer_interface shm_buffer_interface = {
shm_buffer_destroy
};
static struct wl_shm_buffer *
wl_shm_buffer_init(struct wl_client *client, uint32_t id,
int32_t width, int32_t height,
int32_t stride, uint32_t format, void *data)
{
struct wl_shm_buffer *buffer;
buffer = calloc(1, sizeof *buffer);
if (buffer == NULL)
return NULL;
buffer->buffer.width = width;
buffer->buffer.height = height;
buffer->format = format;
buffer->stride = stride;
buffer->data = data;
buffer->buffer.resource.object.id = id;
buffer->buffer.resource.object.interface = &wl_buffer_interface;
buffer->buffer.resource.object.implementation = (void (**)(void))
&shm_buffer_interface;
buffer->buffer.resource.data = buffer;
buffer->buffer.resource.client = client;
buffer->buffer.resource.destroy = destroy_buffer;
return buffer;
}
static void
shm_create_buffer(struct wl_client *client, struct wl_resource *resource,
uint32_t id, int fd, int32_t width, int32_t height,
int32_t stride, uint32_t format)
shm_pool_create_buffer(struct wl_client *client, struct wl_resource *resource,
uint32_t id, int32_t offset,
int32_t width, int32_t height,
int32_t stride, uint32_t format)
{
struct wl_shm_pool *pool = resource->data;
struct wl_shm_buffer *buffer;
void *data;
switch (format) {
case WL_SHM_FORMAT_ARGB8888:
@ -107,43 +97,111 @@ shm_create_buffer(struct wl_client *client, struct wl_resource *resource,
wl_resource_post_error(resource,
WL_SHM_ERROR_INVALID_FORMAT,
"invalid format");
close(fd);
return;
}
if (width < 0 || height < 0 || stride < width) {
if (offset < 0 || width <= 0 || height <= 0 || stride < width ||
INT32_MAX / stride <= height ||
offset > pool->size - stride * height) {
wl_resource_post_error(resource,
WL_SHM_ERROR_INVALID_STRIDE,
"invalid width, height or stride (%dx%d, %u)",
width, height, stride);
return;
}
buffer = malloc(sizeof *buffer);
if (buffer == NULL) {
wl_resource_post_no_memory(resource);
return;
}
buffer->buffer.width = width;
buffer->buffer.height = height;
buffer->format = format;
buffer->stride = stride;
buffer->data = pool->data + offset;
buffer->pool = pool;
pool->refcount++;
buffer->buffer.resource.object.id = id;
buffer->buffer.resource.object.interface = &wl_buffer_interface;
buffer->buffer.resource.object.implementation = (void (**)(void))
&shm_buffer_interface;
buffer->buffer.resource.data = buffer;
buffer->buffer.resource.client = resource->client;
buffer->buffer.resource.destroy = destroy_buffer;
wl_client_add_resource(client, &buffer->buffer.resource);
}
static void
destroy_pool(struct wl_resource *resource)
{
struct wl_shm_pool *pool = resource->data;
shm_pool_unref(pool);
}
static void
shm_pool_destroy(struct wl_client *client, struct wl_resource *resource)
{
wl_resource_destroy(resource, 0);
}
struct wl_shm_pool_interface shm_pool_interface = {
shm_pool_create_buffer,
shm_pool_destroy
};
static void
shm_create_pool(struct wl_client *client, struct wl_resource *resource,
uint32_t id, int fd, int32_t size)
{
struct wl_shm_pool *pool;
pool = malloc(sizeof *pool);
if (pool == NULL) {
wl_resource_post_no_memory(resource);
close(fd);
return;
}
data = mmap(NULL, stride * height,
PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if (size <= 0) {
wl_resource_post_error(resource,
WL_SHM_ERROR_INVALID_STRIDE,
"invalid size (%d)", size);
close(fd);
return;
}
pool->refcount = 1;
pool->size = size;
pool->data = mmap(NULL, size,
PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
close(fd);
if (data == MAP_FAILED) {
if (pool->data == MAP_FAILED) {
wl_resource_post_error(resource,
WL_SHM_ERROR_INVALID_FD,
"failed mmap fd %d", fd);
return;
}
buffer = wl_shm_buffer_init(client, id,
width, height, stride, format, data);
if (buffer == NULL) {
munmap(data, stride * height);
wl_resource_post_no_memory(resource);
return;
}
pool->resource.object.id = id;
pool->resource.object.interface = &wl_shm_pool_interface;
pool->resource.object.implementation =
(void (**)(void)) &shm_pool_interface;
wl_client_add_resource(client, &buffer->buffer.resource);
pool->resource.data = pool;
pool->resource.client = client;
pool->resource.destroy = destroy_pool;
wl_client_add_resource(client, &pool->resource);
}
static const struct wl_shm_interface shm_interface = {
shm_create_buffer
shm_create_pool
};
static void