Re: [PATCH 2/2] liburing: Use the single mmap feature

[Jens Axboe <axboe@xxxxxxxxx>]

On 9/6/19 1:12 PM, Hristo Venev wrote:
> Signed-off-by: Hristo Venev <hristo@xxxxxxxxxx>
> ---
>   src/setup.c | 35 ++++++++++++++++++++++++++---------
>   1 file changed, 26 insertions(+), 9 deletions(-)
> 
> diff --git a/src/setup.c b/src/setup.c
> index 47b0deb..48c96a0 100644
> --- a/src/setup.c
> +++ b/src/setup.c
> @@ -16,10 +16,30 @@ static int io_uring_mmap(int fd, struct io_uring_params *p,
>   	int ret;
>   
>   	sq->ring_sz = p->sq_off.array + p->sq_entries * sizeof(unsigned);
> +	cq->ring_sz = p->cq_off.cqes + p->cq_entries * sizeof(struct io_uring_cqe);
> +
> +	if (p->features & IORING_FEAT_SINGLE_MMAP) {
> +		if (cq->ring_sz > sq->ring_sz) {
> +			sq->ring_sz = cq->ring_sz;
> +		}
> +		cq->ring_sz = sq->ring_sz;
> +	}
>   	sq->ring_ptr = mmap(0, sq->ring_sz, PROT_READ | PROT_WRITE,
>   			MAP_SHARED | MAP_POPULATE, fd, IORING_OFF_SQ_RING);
>   	if (sq->ring_ptr == MAP_FAILED)
>   		return -errno;
> +
> +	if (p->features & IORING_FEAT_SINGLE_MMAP) {
> +		cq->ring_ptr = sq->ring_ptr;
> +	} else {
> +		cq->ring_ptr = mmap(0, cq->ring_sz, PROT_READ | PROT_WRITE,
> +				MAP_SHARED | MAP_POPULATE, fd, IORING_OFF_CQ_RING);
> +		if (cq->ring_ptr == MAP_FAILED) {
> +			ret = -errno;
> +			goto err;
> +		}
> +	}
> +
>   	sq->khead = sq->ring_ptr + p->sq_off.head;
>   	sq->ktail = sq->ring_ptr + p->sq_off.tail;
>   	sq->kring_mask = sq->ring_ptr + p->sq_off.ring_mask;
> @@ -34,19 +54,14 @@ static int io_uring_mmap(int fd, struct io_uring_params *p,
>   				IORING_OFF_SQES);
>   	if (sq->sqes == MAP_FAILED) {
>   		ret = -errno;
> +		if (cq->ring_ptr != sq->ring_ptr) {
> +			munmap(cq->ring_ptr, cq->ring_sz);
> +		}
>   err:
>   		munmap(sq->ring_ptr, sq->ring_sz);
>   		return ret;
>   	}
>   
> -	cq->ring_sz = p->cq_off.cqes + p->cq_entries * sizeof(struct io_uring_cqe);
> -	cq->ring_ptr = mmap(0, cq->ring_sz, PROT_READ | PROT_WRITE,
> -			MAP_SHARED | MAP_POPULATE, fd, IORING_OFF_CQ_RING);
> -	if (cq->ring_ptr == MAP_FAILED) {
> -		ret = -errno;
> -		munmap(sq->sqes, *sq->kring_entries * sizeof(struct io_uring_sqe));
> -		goto err;
> -	}
>   	cq->khead = cq->ring_ptr + p->cq_off.head;
>   	cq->ktail = cq->ring_ptr + p->cq_off.tail;
>   	cq->kring_mask = cq->ring_ptr + p->cq_off.ring_mask;
> @@ -105,6 +120,8 @@ void io_uring_queue_exit(struct io_uring *ring)
>   
>   	munmap(sq->sqes, *sq->kring_entries * sizeof(struct io_uring_sqe));
>   	munmap(sq->ring_ptr, sq->ring_sz);
> -	munmap(cq->ring_ptr, cq->ring_sz);
> +	if (cq->ring_ptr != sq->ring_ptr) {
> +		munmap(cq->ring_ptr, cq->ring_sz);
> +	}
>   	close(ring->ring_fd);
>   }

Thanks, applied.

-- 
Jens Axboe