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greybus: create a slab cache for simple messages
A large number of request and response message types have no payload. Such "simple" messages have a known, fixed maximum size, so we can preallocate and use a pool (slab cache) of them. Here are two benefits to doing this: - There can be (small) performance and memory utilization benefits to using a slab cache. - Error responses can be sent with no payload; the cache is likely to have a free entry to use for an error response even in a low memory situation. The plan here is that an incoming request handler that has no response payload to fill will not need to allocate a response message. If no message has been allocated when a response is to be sent, one will be allocated from the cache by the core code. Signed-off-by: Alex Elder <elder@linaro.org> Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
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parent
835fb5e498
commit
0cffcac305
1 changed files with 49 additions and 11 deletions
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@ -28,6 +28,7 @@
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#define GB_OPERATION_MESSAGE_SIZE_MAX 4096
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static struct kmem_cache *gb_operation_cache;
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static struct kmem_cache *gb_simple_message_cache;
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/* Workqueue to handle Greybus operation completions. */
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static struct workqueue_struct *gb_operation_workqueue;
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@ -369,11 +370,19 @@ gb_operation_message_alloc(struct greybus_host_device *hd, u8 type,
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hd->buffer_size_max = GB_OPERATION_MESSAGE_SIZE_MAX;
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}
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if (message_size > hd->buffer_size_max)
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return NULL;
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/* Allocate the message. Use the slab cache for simple messages */
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if (payload_size) {
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if (message_size > hd->buffer_size_max) {
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pr_warn("requested message size too big (%zu > %zu)\n",
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message_size, hd->buffer_size_max);
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return NULL;
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}
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size = sizeof(*message) + hd->buffer_headroom + message_size;
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message = kzalloc(size, gfp_flags);
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size = sizeof(*message) + hd->buffer_headroom + message_size;
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message = kzalloc(size, gfp_flags);
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} else {
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message = kmem_cache_zalloc(gb_simple_message_cache, gfp_flags);
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}
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if (!message)
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return NULL;
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@ -385,7 +394,10 @@ gb_operation_message_alloc(struct greybus_host_device *hd, u8 type,
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static void gb_operation_message_free(struct gb_message *message)
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{
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kfree(message);
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if (message->size > sizeof(message->header))
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kfree(message);
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else
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kmem_cache_free(gb_simple_message_cache, message);
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}
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/*
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@ -836,22 +848,46 @@ int gb_operation_sync(struct gb_connection *connection, int type,
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int gb_operation_init(void)
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{
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size_t size;
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BUILD_BUG_ON(GB_OPERATION_MESSAGE_SIZE_MAX >
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U16_MAX - sizeof(struct gb_operation_msg_hdr));
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/*
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* A message structure with consists of:
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* - the message structure itself
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* - the headroom set aside for the host device
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* - the message header
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* - space for the message payload
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* Messages with no payload are a fairly common case and
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* have a known fixed maximum size, so we use a slab cache
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* for them.
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*/
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size = sizeof(struct gb_message) + GB_BUFFER_HEADROOM_MAX +
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sizeof(struct gb_operation_msg_hdr);
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gb_simple_message_cache = kmem_cache_create("gb_simple_message_cache",
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size, 0, 0, NULL);
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if (!gb_simple_message_cache)
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return -ENOMEM;
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gb_operation_cache = kmem_cache_create("gb_operation_cache",
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sizeof(struct gb_operation), 0, 0, NULL);
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if (!gb_operation_cache)
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return -ENOMEM;
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goto err_simple;
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gb_operation_workqueue = alloc_workqueue("greybus_operation", 0, 1);
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if (!gb_operation_workqueue) {
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kmem_cache_destroy(gb_operation_cache);
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gb_operation_cache = NULL;
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return -ENOMEM;
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}
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if (!gb_operation_workqueue)
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goto err_operation;
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return 0;
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err_operation:
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kmem_cache_destroy(gb_operation_cache);
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gb_operation_cache = NULL;
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err_simple:
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kmem_cache_destroy(gb_simple_message_cache);
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gb_simple_message_cache = NULL;
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return -ENOMEM;
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}
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void gb_operation_exit(void)
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@ -860,4 +896,6 @@ void gb_operation_exit(void)
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gb_operation_workqueue = NULL;
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kmem_cache_destroy(gb_operation_cache);
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gb_operation_cache = NULL;
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kmem_cache_destroy(gb_simple_message_cache);
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gb_simple_message_cache = NULL;
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}
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