Patch "IB/mlx5: Use cache line size to select CQE stride" has been added to the 4.8-stable tree

This is a note to let you know that I've just added the patch titled

IB/mlx5: Use cache line size to select CQE stride

to the 4.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ib-mlx5-use-cache-line-size-to-select-cqe-stride.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Daniel Jurgens <[email protected]>
Date: Thu, 27 Oct 2016 16:36:41 +0300
Subject: IB/mlx5: Use cache line size to select CQE stride

From: Daniel Jurgens <[email protected]>

commit 16b0e0695a73b68d8ca40288c8f9614ef208917b upstream.

When creating kernel CQs use 128B CQE stride if the cache line size is 128B, 64B otherwise. This prevents multiple CQEs from residing in a 128B cache line, which can cause retries when there are concurrent read and writes in one cache line.

Tested with IPoIB on PPC64, saw ~5% throughput
improvement.

---
 drivers/infiniband/hw/mlx5/cq.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

@@ -917,8 +917,7 @@ struct ib_cq *mlx5_ib_create_cq(struct i
 		if (err)
 			goto err_create;
 	} else {
-		/* for now choose 64 bytes till we have a proper interface */
-		cqe_size = 64;
+		cqe_size = cache_line_size() == 128 ? 128 : 64;
 		err = create_cq_kernel(dev, cq, entries, cqe_size, &cqb,
 				       &index, &inlen);
 		if (err)

Patches currently in stable-queue which might be from [email protected] are

queue-4.8/ib-mlx5-use-cache-line-size-to-select-cqe-stride.patch queue-4.8/ib-mlx4-check-gid_index-return-value.patch queue-4.8/ib-mlx4-fix-create-cq-error-flow.patch