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Subject[PATCH AUTOSEL 5.13 057/189] RDMA/rtrs: Change MAX_SESS_QUEUE_DEPTH
Date
From: Gioh Kim <gi-oh.kim@cloud.ionos.com>

[ Upstream commit 3a98ea7041b7d18ac356da64823c2ba2f8391b3e ]

Max IB immediate data size is 2^28 (MAX_IMM_PAYL_BITS)
and the minimum chunk size is 4096 (2^12).
Therefore the maximum sess_queue_depth is 65536 (2^16).

Link: https://lore.kernel.org/r/20210528113018.52290-6-jinpu.wang@ionos.com
Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/infiniband/ulp/rtrs/rtrs-pri.h | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/infiniband/ulp/rtrs/rtrs-pri.h b/drivers/infiniband/ulp/rtrs/rtrs-pri.h
index 86e65cf30cab..d957bbf1ddd3 100644
--- a/drivers/infiniband/ulp/rtrs/rtrs-pri.h
+++ b/drivers/infiniband/ulp/rtrs/rtrs-pri.h
@@ -47,12 +47,15 @@ enum {
MAX_PATHS_NUM = 128,

/*
- * With the size of struct rtrs_permit allocated on the client, 4K
- * is the maximum number of rtrs_permits we can allocate. This number is
- * also used on the client to allocate the IU for the user connection
- * to receive the RDMA addresses from the server.
+ * Max IB immediate data size is 2^28 (MAX_IMM_PAYL_BITS)
+ * and the minimum chunk size is 4096 (2^12).
+ * So the maximum sess_queue_depth is 65536 (2^16) in theory.
+ * But mempool_create, create_qp and ib_post_send fail with
+ * "cannot allocate memory" error if sess_queue_depth is too big.
+ * Therefore the pratical max value of sess_queue_depth is
+ * somewhere between 1 and 65536 and it depends on the system.
*/
- MAX_SESS_QUEUE_DEPTH = 4096,
+ MAX_SESS_QUEUE_DEPTH = 65536,

RTRS_HB_INTERVAL_MS = 5000,
RTRS_HB_MISSED_MAX = 5,
--
2.30.2
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