From 6ed966cff0d28540ebd5d974a274e4382a31c880 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 28 Sep 2011 10:51:09 +1000 Subject: [PATCH] dio: 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: Andi Kleen Acked-by: Jeff Moyer Cc: Jens Axboe Cc: Christoph Hellwig Signed-off-by: Andrew Morton <> --- fs/direct-io.c | 31 ++++++++++++++++++------------- 1 file changed, 18 insertions(+), 13 deletions(-) diff --git a/fs/direct-io.c b/fs/direct-io.c index 9763009806b4..716ee23f3053 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -199,7 +199,7 @@ static inline unsigned dio_pages_present(struct dio *dio, struct dio_submit *sdi /* * 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 +245,7 @@ out: * 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(dio, sdio) == 0) { int ret; @@ -376,7 +376,7 @@ void dio_end_io(struct bio *bio, int error) } EXPORT_SYMBOL_GPL(dio_end_io); -static void +static void inline dio_bio_alloc(struct dio *dio, struct dio_submit *sdio, struct block_device *bdev, sector_t first_sector, int nr_vecs) @@ -407,7 +407,7 @@ 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 +435,7 @@ 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(dio, sdio)) page_cache_release(dio_get_page(dio, sdio)); @@ -528,7 +528,7 @@ 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; @@ -627,7 +627,7 @@ 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; @@ -653,7 +653,7 @@ out: * * Return zero on success. Non-zero means the caller needs to start a new BIO. */ -static int dio_bio_add_page(struct dio *dio, struct dio_submit *sdio) +static inline int dio_bio_add_page(struct dio *dio, struct dio_submit *sdio) { int ret; @@ -685,8 +685,8 @@ static int dio_bio_add_page(struct dio *dio, 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, - struct buffer_head *map_bh) +static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio, + struct buffer_head *map_bh) { int ret = 0; @@ -755,7 +755,7 @@ out: * 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) @@ -838,7 +838,7 @@ 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, +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; @@ -1035,7 +1035,7 @@ out: 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, @@ -1209,6 +1209,11 @@ 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, -- 2.39.5