----- Original Message -----
> From: "Christoph Hellwig" <h...@infradead.org>
> To: "Laurence Oberman" <lober...@redhat.com>
> Cc: "Christoph Hellwig" <h...@infradead.org>, "Bart Van Assche"
> <bart.vanass...@sandisk.com>,
> linux-r...@vger.kernel.org, linux-scsi@vger.kernel.org
> Sent: Thursday, December 22, 2016 10:40:49 AM
> Subject: Re: Testing latest linux-next 4.9 ib_srp and ib_srpt sees I/O capped
> at 1MB and no merging
>
> Hi Laurance,
>
> please try the patch below:
>
> ---
> From 69febe1cfb55844862f768447432249781001f9c Mon Sep 17 00:00:00 2001
> From: Christoph Hellwig <h...@lst.de>
> Date: Thu, 22 Dec 2016 16:38:29 +0100
> Subject: block: add back plugging in __blkdev_direct_IO
>
> This allows sending larger than 1 MB requess to devices that support
> large I/O sizes.
>
> Signed-off-by: Christoph Hellwig <h...@lst.de>
> Reported-by: Laurence Oberman <lober...@redhat.com>
> ---
> fs/block_dev.c | 3 +++
> fs/iomap.c | 1 -
> 2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index 7c45072..206a92a 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -328,6 +328,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter
> *iter, int nr_pages)
> struct file *file = iocb->ki_filp;
> struct inode *inode = bdev_file_inode(file);
> struct block_device *bdev = I_BDEV(inode);
> + struct blk_plug plug;
> struct blkdev_dio *dio;
> struct bio *bio;
> bool is_read = (iov_iter_rw(iter) == READ);
> @@ -353,6 +354,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter
> *iter, int nr_pages)
> dio->multi_bio = false;
> dio->should_dirty = is_read && (iter->type == ITER_IOVEC);
>
> + blk_start_plug(&plug);
> for (;;) {
> bio->bi_bdev = bdev;
> bio->bi_iter.bi_sector = pos >> 9;
> @@ -394,6 +396,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter
> *iter, int nr_pages)
> submit_bio(bio);
> bio = bio_alloc(GFP_KERNEL, nr_pages);
> }
> + blk_finish_plug(&plug);
>
> if (!dio->is_sync)
> return -EIOCBQUEUED;
> diff --git a/fs/iomap.c b/fs/iomap.c
> index 354a123..3adf1e1 100644
> --- a/fs/iomap.c
> +++ b/fs/iomap.c
> @@ -844,7 +844,6 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
> struct iomap_ops *ops,
> size_t count = iov_iter_count(iter);
> loff_t pos = iocb->ki_pos, end = iocb->ki_pos + count - 1, ret = 0;
> unsigned int flags = IOMAP_DIRECT;
> - struct blk_plug plug;
> struct iomap_dio *dio;
>
> lockdep_assert_held(&inode->i_rwsem);
> --
> 2.1.4
>
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>
Hello Christoph
The patch works and I now see 4MB I/O
# DISK STATISTICS (/sec)
#
<---------reads---------><---------writes---------><--------averages-------->
Pct
#Time Name KBytes Merged IOs Size KBytes Merged IOs Size RWSize
QLen Wait SvcTim Util
11:53:58 sdah 143360 105 35 4096 0 0 0 0 4096
1 28 28 99
11:53:59 sdah 139264 102 34 4096 0 0 0 0 4096
1 29 29 99
11:54:00 sdah 143360 105 35 4096 0 0 0 0 4096
1 28 28 99
I think you forgot to remove calls to blk_start_plug and blk_finish_plug in
fs/iomap.c in your patch.
I took them out and built the test kernel that way.
Let me know if you will just remove those in the final or want a patch.
Thanks fo rthe super quick response
Regards
Laurence
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