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Commit ba253fbf authored by Andi Kleen's avatar Andi Kleen Committed by root
Browse files

direct-io: inline the complete submission path 



Add inlines to all the submission path functions. While this increases
code size it also gives gcc a lot of optimization opportunities
in this critical hotpath.

In particular -- together with some other changes -- this
allows gcc to get rid of the unnecessary clearing of
sdio at the beginning and optimize the messy parameter passing.
Any non inlining of a function which takes a sdio parameter
would break this optimization because they cannot be done if the
address of a structure is taken.

Note that benefits are only seen with CONFIG_OPTIMIZE_INLINING
and CONFIG_CC_OPTIMIZE_FOR_SIZE both set to off.

This gives about 2.2% improvement on a large database benchmark
with a high IOPS rate.

Signed-off-by: default avatarAndi Kleen <ak@linux.intel.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 18772641

fs/direct-io.c

+21 −15
Original line number Diff line number Diff line
@@ -199,7 +199,7 @@ static inline unsigned dio_pages_present(struct dio_submit *sdio) 
/*

 * Go grab and pin some userspace pages.   Typically we'll get 64 at a time.

 */

static int dio_refill_pages(struct dio *dio, struct dio_submit *sdio)

static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio)

{

	int ret;

	int nr_pages;
@@ -245,7 +245,8 @@ static int dio_refill_pages(struct dio *dio, struct dio_submit *sdio) 
 * decent number of pages, less frequently.  To provide nicer use of the

 * L1 cache.

 */

static struct page *dio_get_page(struct dio *dio, struct dio_submit *sdio)

static inline struct page *dio_get_page(struct dio *dio,

		struct dio_submit *sdio)

{

	if (dio_pages_present(sdio) == 0) {

		int ret;
@@ -376,7 +377,7 @@ void dio_end_io(struct bio *bio, int error) 
}

EXPORT_SYMBOL_GPL(dio_end_io);



static void

static inline void

dio_bio_alloc(struct dio *dio, struct dio_submit *sdio,

	      struct block_device *bdev,

	      sector_t first_sector, int nr_vecs)
@@ -407,7 +408,7 @@ dio_bio_alloc(struct dio *dio, struct dio_submit *sdio, 
 *

 * bios hold a dio reference between submit_bio and ->end_io.

 */

static void dio_bio_submit(struct dio *dio, struct dio_submit *sdio)

static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio)

{

	struct bio *bio = sdio->bio;

	unsigned long flags;
@@ -435,7 +436,7 @@ static void dio_bio_submit(struct dio *dio, struct dio_submit *sdio) 
/*

 * Release any resources in case of a failure

 */

static void dio_cleanup(struct dio *dio, struct dio_submit *sdio)

static inline void dio_cleanup(struct dio *dio, struct dio_submit *sdio)

{

	while (dio_pages_present(sdio))

		page_cache_release(dio_get_page(dio, sdio));
@@ -528,7 +529,7 @@ static void dio_await_completion(struct dio *dio) 
 *

 * This also helps to limit the peak amount of pinned userspace memory.

 */

static int dio_bio_reap(struct dio *dio, struct dio_submit *sdio)

static inline int dio_bio_reap(struct dio *dio, struct dio_submit *sdio)

{

	int ret = 0;
@@ -631,7 +632,7 @@ static int get_more_blocks(struct dio *dio, struct dio_submit *sdio, 
/*

 * There is no bio.  Make one now.

 */

static int dio_new_bio(struct dio *dio, struct dio_submit *sdio,

static inline int dio_new_bio(struct dio *dio, struct dio_submit *sdio,

		sector_t start_sector, struct buffer_head *map_bh)

{

	sector_t sector;
@@ -657,7 +658,7 @@ static int dio_new_bio(struct dio *dio, struct dio_submit *sdio, 
 *

 * Return zero on success.  Non-zero means the caller needs to start a new BIO.

 */

static int dio_bio_add_page(struct dio_submit *sdio)

static inline int dio_bio_add_page(struct dio_submit *sdio)

{

	int ret;
@@ -689,7 +690,7 @@ static int dio_bio_add_page(struct dio_submit *sdio) 
 * The caller of this function is responsible for removing cur_page from the

 * dio, and for dropping the refcount which came from that presence.

 */

static int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio,

static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio,

		struct buffer_head *map_bh)

{

	int ret = 0;
@@ -759,7 +760,7 @@ static int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio, 
 * If that doesn't work out then we put the old page into the bio and add this

 * page to the dio instead.

 */

static int

static inline int

submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page,

		    unsigned offset, unsigned len, sector_t blocknr,

		    struct buffer_head *map_bh)
@@ -842,8 +843,8 @@ static void clean_blockdev_aliases(struct dio *dio, struct buffer_head *map_bh) 
 * `end' is zero if we're doing the start of the IO, 1 at the end of the

 * IO.

 */

static void dio_zero_block(struct dio *dio, struct dio_submit *sdio, int end,

			   struct buffer_head *map_bh)

static inline void dio_zero_block(struct dio *dio, struct dio_submit *sdio,

		int end, struct buffer_head *map_bh)

{

	unsigned dio_blocks_per_fs_block;

	unsigned this_chunk_blocks;	/* In dio_blocks */
@@ -1042,7 +1043,7 @@ static int do_direct_IO(struct dio *dio, struct dio_submit *sdio, 
	return ret;

}



static ssize_t

static inline ssize_t

direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, 

	const struct iovec *iov, loff_t offset, unsigned long nr_segs, 

	unsigned blkbits, get_block_t get_block, dio_iodone_t end_io,
@@ -1216,6 +1217,11 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, 
 * expected that filesystem provide exclusion between new direct I/O

 * and truncates.  For DIO_LOCKING filesystems this is done by i_mutex,

 * but other filesystems need to take care of this on their own.

 *

 * NOTE: if you pass "sdio" to anything by pointer make sure that function

 * is always inlined. Otherwise gcc is unable to split the structure into

 * individual fields and will generate much worse code. This is important

 * for the whole file.

 */

ssize_t

__blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,