On Thu, Jul 24, 2014 at 6:55 AM, Ming Lei <ming....@canonical.com> wrote:
> Part of the patch is based on Dave's previous post.
>
> It is easy to observe that loop block device thoughput
> can be increased by > 100% in single job randread,
> libaio engine, direct I/O fio test.
>
> Cc: Zach Brown <z...@zabbo.net>
> Cc: Dave Kleikamp <dave.kleik...@oracle.com>
> Cc: Benjamin LaHaise <b...@kvack.org>
> Signed-off-by: Ming Lei <ming....@canonical.com>
> ---
> drivers/block/loop.c | 128
> ++++++++++++++++++++++++++++++++++++++++++---
> drivers/block/loop.h | 1 +
> include/uapi/linux/loop.h | 1 +
> 3 files changed, 122 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index 96a8913..2279d26 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> +static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
> + bool write, loff_t pos)
> +{
> + struct file *file = lo->lo_backing_file;
> + struct request *rq = cmd->rq;
> + struct kiocb *iocb;
> + unsigned int op, i = 0;
> + struct iov_iter iter;
> + struct bio_vec *bvec, bv;
> + size_t nr_segs = 0;
> + struct req_iterator r_iter;
> + int ret = -EIO;
> +
> + /* how many segments */
> + rq_for_each_segment(bv, rq, r_iter)
> + nr_segs++;
> +
> + iocb = aio_kernel_alloc(GFP_NOIO, nr_segs * sizeof(*bvec));
> + if (!iocb) {
> + ret = -ENOMEM;
> + goto failed;
> + }
> +
> + cmd->iocb = iocb;
> + bvec = (struct bio_vec *)(iocb + 1);
> + rq_for_each_segment(bv, rq, r_iter)
> + bvec[i++] = bv;
> +
> + if (write)
> + op = IOCB_CMD_WRITE_ITER;
> + else
> + op = IOCB_CMD_READ_ITER;
> +
> + iter.type = ITER_BVEC | (write ? WRITE : 0);
> + iter.bvec = bvec;
> + iter.nr_segs = nr_segs;
> + iter.count = blk_rq_bytes(rq);
> + iter.iov_offset = 0;
> +
> + aio_kernel_init_rw(iocb, file, iov_iter_count(&iter), pos,
> + lo_rw_aio_complete, (u64)(uintptr_t)cmd);
> + ret = aio_kernel_submit(iocb, op, &iter);
> +
> + /*
> + * use same policy with userspace aio, req may have been
> + * completed already, so relase it by aio completion.
> + */
> + if (ret != -EIOCBQUEUED)
> + lo_rw_aio_complete((u64)cmd, ret);
The above stuff should have been put inside aio_kernel_submit(),
will do it in V1.
Thanks,
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
