IB/mthca: Always fill MTTs from CPU

Speed up memory registration by filling in MTTs directly when the CPU
can write directly to the whole table (all mem-free cards, and to
Tavor mode on 64-bit systems with the patch I posted earlier).  This
reduces the number of FW commands needed to register an MR by at least
a factor of 2 and speeds up memory registration significantly.

Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 7 insertions, 7 deletions

diff --git a/drivers/infiniband/hw/mthca/mthca_provider.c b/drivers/infiniband/hw/mthca/mthca_provider.c
index 7b96751695ea..0725ad7ad9bf 100644
--- a/drivers/infiniband/hw/mthca/mthca_provider.c
+++ b/drivers/infiniband/hw/mthca/mthca_provider.c
@@ -1015,6 +1015,7 @@ static struct ib_mr *mthca_reg_user_mr(struct ib_pd *pd, struct ib_umem *region,
         int shift, n, len;
         int i, j, k;
         int err = 0;
+        int write_mtt_size;
 
         shift = ffs(region->page_size) - 1;
 
@@ -1040,6 +1041,8 @@ static struct ib_mr *mthca_reg_user_mr(struct ib_pd *pd, struct ib_umem *region,
 
         i = n = 0;
 
+        write_mtt_size = min(mthca_write_mtt_size(dev), (int) (PAGE_SIZE / sizeof *pages));
+
         list_for_each_entry(chunk, &region->chunk_list, list)
                 for (j = 0; j < chunk->nmap; ++j) {
                         len = sg_dma_len(&chunk->page_list[j]) >> shift;
@@ -1047,14 +1050,11 @@ static struct ib_mr *mthca_reg_user_mr(struct ib_pd *pd, struct ib_umem *region,
                                 pages[i++] = sg_dma_address(&chunk->page_list[j]) +
                                         region->page_size * k;
                                 /*
-                                 * Be friendly to WRITE_MTT command
-                                 * and leave two empty slots for the
-                                 * index and reserved fields of the
-                                 * mailbox.
+                                 * Be friendly to write_mtt and pass it chunks
+                                 * of appropriate size.
                                  */
-                                if (i == PAGE_SIZE / sizeof (u64) - 2) {
-                                        err = mthca_write_mtt(dev, mr->mtt,
-                                                              n, pages, i);
+                                if (i == write_mtt_size) {
+                                        err = mthca_write_mtt(dev, mr->mtt, n, pages, i);
                                         if (err)
                                                 goto mtt_done;
                                         n += i;