From 09ce8744253a038eb658c14f9dc3b77fa021fc9f Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 14 Oct 2021 11:17:43 -0600 Subject: [PATCH] block: use flags instead of bit fields for blkdev_dio This generates a lot better code for me, and bumps performance from 7650K IOPS to 7750K IOPS. Looking at profiles for the run and running perf diff, it confirms that we're now sending a lot less time there: 6.38% -2.80% [kernel.vmlinux] [k] blkdev_direct_IO Taking it from the 2nd most cycle consumer to only the 9th most at 3.35% of the CPU time. Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe --- block/fops.c | 34 ++++++++++++++++++++-------------- 1 file changed, 20 insertions(+), 14 deletions(-) diff --git a/block/fops.c b/block/fops.c index 551b71af6d90..1d4f862950bb 100644 --- a/block/fops.c +++ b/block/fops.c @@ -123,6 +123,12 @@ out: return ret; } +enum { + DIO_MULTI_BIO = 1, + DIO_SHOULD_DIRTY = 2, + DIO_IS_SYNC = 4, +}; + struct blkdev_dio { union { struct kiocb *iocb; @@ -130,9 +136,7 @@ struct blkdev_dio { }; size_t size; atomic_t ref; - bool multi_bio : 1; - bool should_dirty : 1; - bool is_sync : 1; + unsigned int flags; struct bio bio; }; @@ -141,13 +145,13 @@ static struct bio_set blkdev_dio_pool; static void blkdev_bio_end_io(struct bio *bio) { struct blkdev_dio *dio = bio->bi_private; - bool should_dirty = dio->should_dirty; + bool should_dirty = dio->flags & DIO_SHOULD_DIRTY; if (bio->bi_status && !dio->bio.bi_status) dio->bio.bi_status = bio->bi_status; - if (!dio->multi_bio || atomic_dec_and_test(&dio->ref)) { - if (!dio->is_sync) { + if (!(dio->flags & DIO_MULTI_BIO) || atomic_dec_and_test(&dio->ref)) { + if (!(dio->flags & DIO_IS_SYNC)) { struct kiocb *iocb = dio->iocb; ssize_t ret; @@ -161,7 +165,7 @@ static void blkdev_bio_end_io(struct bio *bio) } dio->iocb->ki_complete(iocb, ret, 0); - if (dio->multi_bio) + if (dio->flags & DIO_MULTI_BIO) bio_put(&dio->bio); } else { struct task_struct *waiter = dio->waiter; @@ -198,17 +202,19 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, bio = bio_alloc_kiocb(iocb, nr_pages, &blkdev_dio_pool); dio = container_of(bio, struct blkdev_dio, bio); - dio->is_sync = is_sync = is_sync_kiocb(iocb); - if (dio->is_sync) { + is_sync = is_sync_kiocb(iocb); + if (is_sync) { + dio->flags = DIO_IS_SYNC; dio->waiter = current; bio_get(bio); } else { + dio->flags = 0; dio->iocb = iocb; } dio->size = 0; - dio->multi_bio = false; - dio->should_dirty = is_read && iter_is_iovec(iter); + if (is_read && iter_is_iovec(iter)) + dio->flags |= DIO_SHOULD_DIRTY; /* * Don't plug for HIPRI/polled IO, as those should go straight @@ -234,7 +240,7 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, if (is_read) { bio->bi_opf = REQ_OP_READ; - if (dio->should_dirty) + if (dio->flags & DIO_SHOULD_DIRTY) bio_set_pages_dirty(bio); } else { bio->bi_opf = dio_bio_write_op(iocb); @@ -255,7 +261,7 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, WRITE_ONCE(iocb->private, bio); break; } - if (!dio->multi_bio) { + if (!(dio->flags & DIO_MULTI_BIO)) { /* * AIO needs an extra reference to ensure the dio * structure which is embedded into the first bio @@ -263,7 +269,7 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, */ if (!is_sync) bio_get(bio); - dio->multi_bio = true; + dio->flags |= DIO_MULTI_BIO; atomic_set(&dio->ref, 2); do_poll = false; } else { -- 2.11.0