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authorChuck Lever <chuck.lever@oracle.com>2018-12-19 10:58:51 -0500
committerAnna Schumaker <Anna.Schumaker@Netapp.com>2019-01-02 12:05:17 -0500
commita78868497c2e4858e2c73818eed7b4877ab2316d (patch)
tree9d57c46b0b6584e3d60524deb345865d0142a980 /net
parent6946f82380a83acb7023fab9d7033e1f016cb818 (diff)
downloadlinux-a78868497c2e4858e2c73818eed7b4877ab2316d.tar.bz2
xprtrdma: Reduce max_frwr_depth
Some devices advertise a large max_fast_reg_page_list_len capability, but perform optimally when MRs are significantly smaller than that depth -- probably when the MR itself is no larger than a page. By default, the RDMA R/W core API uses max_sge_rd as the maximum page depth for MRs. For some devices, the value of max_sge_rd is 1, which is also not optimal. Thus, when max_sge_rd is larger than 1, use that value. Otherwise use the value of the max_fast_reg_page_list_len attribute. I've tested this with CX-3 Pro, FastLinq, and CX-5 devices. It reproducibly improves the throughput of large I/Os by several percent. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'net')
-rw-r--r--net/sunrpc/xprtrdma/frwr_ops.c15
1 files changed, 11 insertions, 4 deletions
diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c
index f587e445d811..16976b031865 100644
--- a/net/sunrpc/xprtrdma/frwr_ops.c
+++ b/net/sunrpc/xprtrdma/frwr_ops.c
@@ -193,10 +193,17 @@ frwr_op_open(struct rpcrdma_ia *ia, struct rpcrdma_ep *ep,
if (attrs->device_cap_flags & IB_DEVICE_SG_GAPS_REG)
ia->ri_mrtype = IB_MR_TYPE_SG_GAPS;
- ia->ri_max_frwr_depth =
- min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS,
- attrs->max_fast_reg_page_list_len);
- dprintk("RPC: %s: device's max FR page list len = %u\n",
+ /* Quirk: Some devices advertise a large max_fast_reg_page_list_len
+ * capability, but perform optimally when the MRs are not larger
+ * than a page.
+ */
+ if (attrs->max_sge_rd > 1)
+ ia->ri_max_frwr_depth = attrs->max_sge_rd;
+ else
+ ia->ri_max_frwr_depth = attrs->max_fast_reg_page_list_len;
+ if (ia->ri_max_frwr_depth > RPCRDMA_MAX_DATA_SEGS)
+ ia->ri_max_frwr_depth = RPCRDMA_MAX_DATA_SEGS;
+ dprintk("RPC: %s: max FR page list depth = %u\n",
__func__, ia->ri_max_frwr_depth);
/* Add room for frwr register and invalidate WRs.