| From 0544f5494a03b8846db74e02be5685d1f32b06c9 Mon Sep 17 00:00:00 2001 |
| From: Marta Rybczynska <mrybczyn@kalray.eu> |
| Date: Mon, 10 Apr 2017 17:12:34 +0200 |
| Subject: nvme-rdma: support devices with queue size < 32 |
| |
| From: Marta Rybczynska <mrybczyn@kalray.eu> |
| |
| commit 0544f5494a03b8846db74e02be5685d1f32b06c9 upstream. |
| |
| In the case of small NVMe-oF queue size (<32) we may enter a deadlock |
| caused by the fact that the IB completions aren't sent waiting for 32 |
| and the send queue will fill up. |
| |
| The error is seen as (using mlx5): |
| [ 2048.693355] mlx5_0:mlx5_ib_post_send:3765:(pid 7273): |
| [ 2048.693360] nvme nvme1: nvme_rdma_post_send failed with error code -12 |
| |
| This patch changes the way the signaling is done so that it depends on |
| the queue depth now. The magic define has been removed completely. |
| |
| Signed-off-by: Marta Rybczynska <marta.rybczynska@kalray.eu> |
| Signed-off-by: Samuel Jones <sjones@kalray.eu> |
| Acked-by: Sagi Grimberg <sagi@grimberg.me> |
| Signed-off-by: Christoph Hellwig <hch@lst.de> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/nvme/host/rdma.c | 18 ++++++++++++++---- |
| 1 file changed, 14 insertions(+), 4 deletions(-) |
| |
| --- a/drivers/nvme/host/rdma.c |
| +++ b/drivers/nvme/host/rdma.c |
| @@ -1011,6 +1011,19 @@ static void nvme_rdma_send_done(struct i |
| nvme_rdma_wr_error(cq, wc, "SEND"); |
| } |
| |
| +static inline int nvme_rdma_queue_sig_limit(struct nvme_rdma_queue *queue) |
| +{ |
| + int sig_limit; |
| + |
| + /* |
| + * We signal completion every queue depth/2 and also handle the |
| + * degenerated case of a device with queue_depth=1, where we |
| + * would need to signal every message. |
| + */ |
| + sig_limit = max(queue->queue_size / 2, 1); |
| + return (++queue->sig_count % sig_limit) == 0; |
| +} |
| + |
| static int nvme_rdma_post_send(struct nvme_rdma_queue *queue, |
| struct nvme_rdma_qe *qe, struct ib_sge *sge, u32 num_sge, |
| struct ib_send_wr *first, bool flush) |
| @@ -1038,9 +1051,6 @@ static int nvme_rdma_post_send(struct nv |
| * Would have been way to obvious to handle this in hardware or |
| * at least the RDMA stack.. |
| * |
| - * This messy and racy code sniplet is copy and pasted from the iSER |
| - * initiator, and the magic '32' comes from there as well. |
| - * |
| * Always signal the flushes. The magic request used for the flush |
| * sequencer is not allocated in our driver's tagset and it's |
| * triggered to be freed by blk_cleanup_queue(). So we need to |
| @@ -1048,7 +1058,7 @@ static int nvme_rdma_post_send(struct nv |
| * embeded in request's payload, is not freed when __ib_process_cq() |
| * calls wr_cqe->done(). |
| */ |
| - if ((++queue->sig_count % 32) == 0 || flush) |
| + if (nvme_rdma_queue_sig_limit(queue) || flush) |
| wr.send_flags |= IB_SEND_SIGNALED; |
| |
| if (first) |