diff options
| author | Guangguan Wang <guangguan.wang@linux.alibaba.com> | 2022-05-16 08:51:37 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-05-18 03:34:12 +0300 |
| commit | 793a7df63071eb09e5b88addf2a569d7bfd3c973 (patch) | |
| tree | c630bccadfc8439ab45543201cf3af316857a7fa /net/smc | |
| parent | b632eb06973209dfac1eba3a9fbd13f0041f3e45 (diff) | |
| download | linux-793a7df63071eb09e5b88addf2a569d7bfd3c973.tar.xz | |
net/smc: rdma write inline if qp has sufficient inline space
Rdma write with inline flag when sending small packages,
whose length is shorter than the qp's max_inline_data, can
help reducing latency.
In my test environment, which are 2 VMs running on the same
physical host and whose NICs(ConnectX-4Lx) are working on
SR-IOV mode, qperf shows 0.5us-0.7us improvement in latency.
Test command:
server: smc_run taskset -c 1 qperf
client: smc_run taskset -c 1 qperf <server ip> -oo \
msg_size:1:2K:*2 -t 30 -vu tcp_lat
The results shown below:
msgsize before after
1B 11.2 us 10.6 us (-0.6 us)
2B 11.2 us 10.7 us (-0.5 us)
4B 11.3 us 10.7 us (-0.6 us)
8B 11.2 us 10.6 us (-0.6 us)
16B 11.3 us 10.7 us (-0.6 us)
32B 11.3 us 10.6 us (-0.7 us)
64B 11.2 us 11.2 us (0 us)
128B 11.2 us 11.2 us (0 us)
256B 11.2 us 11.2 us (0 us)
512B 11.4 us 11.3 us (-0.1 us)
1KB 11.4 us 11.5 us (0.1 us)
2KB 11.5 us 11.5 us (0 us)
Signed-off-by: Guangguan Wang <guangguan.wang@linux.alibaba.com>
Reviewed-by: Tony Lu <tonylu@linux.alibaba.com>
Tested-by: kernel test robot <lkp@intel.com>
Acked-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/smc')
| -rw-r--r-- | net/smc/smc_tx.c | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/net/smc/smc_tx.c b/net/smc/smc_tx.c index 98ca9229fe87..805a546e8c04 100644 --- a/net/smc/smc_tx.c +++ b/net/smc/smc_tx.c @@ -391,12 +391,20 @@ static int smcr_tx_rdma_writes(struct smc_connection *conn, size_t len, int rc; for (dstchunk = 0; dstchunk < 2; dstchunk++) { - struct ib_sge *sge = - wr_rdma_buf->wr_tx_rdma[dstchunk].wr.sg_list; + struct ib_rdma_wr *wr = &wr_rdma_buf->wr_tx_rdma[dstchunk]; + struct ib_sge *sge = wr->wr.sg_list; + u64 base_addr = dma_addr; + + if (dst_len < link->qp_attr.cap.max_inline_data) { + base_addr = (uintptr_t)conn->sndbuf_desc->cpu_addr; + wr->wr.send_flags |= IB_SEND_INLINE; + } else { + wr->wr.send_flags &= ~IB_SEND_INLINE; + } num_sges = 0; for (srcchunk = 0; srcchunk < 2; srcchunk++) { - sge[srcchunk].addr = dma_addr + src_off; + sge[srcchunk].addr = base_addr + src_off; sge[srcchunk].length = src_len; num_sges++; @@ -410,8 +418,7 @@ static int smcr_tx_rdma_writes(struct smc_connection *conn, size_t len, src_len = dst_len - src_len; /* remainder */ src_len_sum += src_len; } - rc = smc_tx_rdma_write(conn, dst_off, num_sges, - &wr_rdma_buf->wr_tx_rdma[dstchunk]); + rc = smc_tx_rdma_write(conn, dst_off, num_sges, wr); if (rc) return rc; if (dst_len_sum == len) |