Commit 48f22f80 authored by Fengnan Chang's avatar Fengnan Chang Committed by Jens Axboe
Browse files

block: enable per-cpu bio cache by default 



Since after commit 12e4e8c7 ("io_uring/rw: enable bio caches for
IRQ rw"), bio_put is safe for task and irq context, bio_alloc_bioset is
safe for task context and no one calls in irq context, so we can enable
per cpu bio cache by default.

Benchmarked with t/io_uring and ext4+nvme:
taskset -c 6 /root/fio/t/io_uring  -p0 -d128 -b4096 -s1 -c1 -F1 -B1 -R1
-X1 -n1 -P1  /mnt/testfile
base IOPS is 562K, patch IOPS is 574K. The CPU usage of bio_alloc_bioset
decrease from 1.42% to 1.22%.

The worst case is allocate bio in CPU A but free in CPU B, still use
t/io_uring and ext4+nvme:
base IOPS is 648K, patch IOPS is 647K.

Also use fio test ext4/xfs with libaio/sync/io_uring on null_blk and
nvme, no obvious performance regression.

Signed-off-by: default avatarFengnan Chang <changfengnan@bytedance.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 05ce4c58

block/bio.c

+12 −14
Original line number Diff line number Diff line
@@ -517,20 +517,18 @@ struct bio *bio_alloc_bioset(struct block_device *bdev, unsigned short nr_vecs, 
	if (WARN_ON_ONCE(!mempool_initialized(&bs->bvec_pool) && nr_vecs > 0))

		return NULL;



	if (opf & REQ_ALLOC_CACHE) {

	if (bs->cache && nr_vecs <= BIO_INLINE_VECS) {

		opf |= REQ_ALLOC_CACHE;

		bio = bio_alloc_percpu_cache(bdev, nr_vecs, opf,

					     gfp_mask, bs);

		if (bio)

			return bio;

		/*

		 * No cached bio available, bio returned below marked with

			 * REQ_ALLOC_CACHE to particpate in per-cpu alloc cache.

		 * REQ_ALLOC_CACHE to participate in per-cpu alloc cache.

		 */

		} else {

	} else

		opf &= ~REQ_ALLOC_CACHE;

		}

	}



	/*

	 * submit_bio_noacct() converts recursion to iteration; this means if

block/fops.c

+0 −4
Original line number Diff line number Diff line
@@ -184,8 +184,6 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, 
	loff_t pos = iocb->ki_pos;

	int ret = 0;



	if (iocb->ki_flags & IOCB_ALLOC_CACHE)

		opf |= REQ_ALLOC_CACHE;

	bio = bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL,

			       &blkdev_dio_pool);

	dio = container_of(bio, struct blkdev_dio, bio);
@@ -333,8 +331,6 @@ static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb, 
	loff_t pos = iocb->ki_pos;

	int ret = 0;



	if (iocb->ki_flags & IOCB_ALLOC_CACHE)

		opf |= REQ_ALLOC_CACHE;

	bio = bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL,

			       &blkdev_dio_pool);

	dio = container_of(bio, struct blkdev_dio, bio);

io_uring/rw.c

+0 −1
Original line number Diff line number Diff line
@@ -855,7 +855,6 @@ static int io_rw_init_file(struct io_kiocb *req, fmode_t mode, int rw_type) 
	ret = kiocb_set_rw_flags(kiocb, rw->flags, rw_type);

	if (unlikely(ret))

		return ret;

	kiocb->ki_flags |= IOCB_ALLOC_CACHE;



	/*

	 * If the file is marked O_NONBLOCK, still allow retry for it if it