From cfb1e33eed48165763edc7a4a067cf5f74898d0b Mon Sep 17 00:00:00 2001 From: Jeff Moyer Date: Fri, 2 Oct 2009 18:57:36 -0400 Subject: aio: implement request batching Hi, Some workloads issue batches of small I/O, and the performance is poor due to the call to blk_run_address_space for every single iocb. Nathan Roberts pointed this out, and suggested that by deferring this call until all I/Os in the iocb array are submitted to the block layer, we can realize some impressive performance gains (up to 30% for sequential 4k reads in batches of 16). Signed-off-by: Jeff Moyer Signed-off-by: Jens Axboe --- fs/direct-io.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'fs/direct-io.c') diff --git a/fs/direct-io.c b/fs/direct-io.c index c86d35f142d..3af761c8c5c 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -1028,9 +1028,6 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, if (dio->bio) dio_bio_submit(dio); - /* All IO is now issued, send it on its way */ - blk_run_address_space(inode->i_mapping); - /* * It is possible that, we return short IO due to end of file. * In that case, we need to release all the pages we got hold on. @@ -1057,8 +1054,11 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, ((rw & READ) || (dio->result == dio->size))) ret = -EIOCBQUEUED; - if (ret != -EIOCBQUEUED) + if (ret != -EIOCBQUEUED) { + /* All IO is now issued, send it on its way */ + blk_run_address_space(inode->i_mapping); dio_await_completion(dio); + } /* * Sync will always be dropping the final ref and completing the -- cgit v1.2.3