rsocket: Reduce SQ from 2 SGE per WR to 1 SGE

We currently request 2 SGEs per WR when allocating a QP.  The
second SGE is only used when sending data at the end of
the circular send buffer and the start.  All other sends are
restricted to a single SGE.

Reduce the size of the SQ by only requesting 1 SGE per WR.  The
resulting performance is basically unaffected.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>

diff --git a/src/rsocket.c b/src/rsocket.c
index 1140975db34117de0bc2ae6209abbca0691f3f5b..529c3b0bfd96bea7a9393e8cd88f982a59fd8c6d 100644 (file)
--- a/src/rsocket.c
+++ b/src/rsocket.c
@@ -90,6 +90,10 @@ enum {
 #define rs_msg_op(imm_data)   (imm_data >> 29)
 #define rs_msg_data(imm_data) (imm_data & 0x1FFFFFFF)
 
+#define rs_wrid_set(sqe, length) ((((uint64_t) sqe) << 32) | ((uint64_t) length))
+#define rs_wrid_len(wrid)        ((uint32_t) wrid)
+#define rs_wrid_sqe(wrid)        1
+
 enum {
        RS_CTRL_DISCONNECT
 };
@@ -118,14 +122,6 @@ struct rs_conn_data {
        struct rs_sge     data_buf;
 };
 
-union rs_wr_id {
-       uint64_t          wr_id;
-       struct {
-               uint32_t  reserved; /* sqe_count; */
-               uint32_t  length;
-       };
-};
-
 enum rs_state {
        rs_init,
        rs_bound,
@@ -189,20 +185,10 @@ struct rsocket {
 
        uint32_t          sbuf_size;
        struct ibv_mr    *smr;
-       struct ibv_sge    ssgl[2];
+       struct ibv_sge    ssge;
        uint8_t           *sbuf;
 };
 
-/*
- * We currently generate a completion per send.  sqe_count = 1
- */
-static union rs_wr_id rs_wrid(uint32_t sqe_count, uint32_t length)
-{
-       union rs_wr_id wrid;
-       /* wrid.reserved = sqe_count; */
-       wrid.length = length;
-       return wrid;
-}
 
 static int rs_insert(struct rsocket *rs)
 {
@@ -307,9 +293,9 @@ static int rs_init_bufs(struct rsocket *rs)
        if (!rs->rmr)
                return -1;
 
-       rs->ssgl[0].addr = rs->ssgl[1].addr = (uintptr_t) rs->sbuf;
+       rs->ssge.addr = (uintptr_t) rs->sbuf;
        rs->sbuf_bytes_avail = rs->sbuf_size;
-       rs->ssgl[0].lkey = rs->ssgl[1].lkey = rs->smr->lkey;
+       rs->ssge.lkey = rs->smr->lkey;
 
        rs->rbuf_free_offset = rs->rbuf_size >> 1;
        rs->rbuf_bytes_avail = rs->rbuf_size >> 1;
@@ -369,7 +355,7 @@ static int rs_create_ep(struct rsocket *rs)
        qp_attr.sq_sig_all = 1;
        qp_attr.cap.max_send_wr = rs->sq_size;
        qp_attr.cap.max_recv_wr = rs->rq_size;
-       qp_attr.cap.max_send_sge = 2;
+       qp_attr.cap.max_send_sge = 1;
        qp_attr.cap.max_recv_sge = 1;
        qp_attr.cap.max_inline_data = rs->sq_inline;
 
@@ -709,35 +695,35 @@ static int rs_post_write(struct rsocket *rs, uint64_t wr_id,
  * Update target SGE before sending data.  Otherwise the remote side may
  * update the entry before we do.
  */
-static int rs_write_data(struct rsocket *rs, union rs_wr_id wr_id,
-                        struct ibv_sge *sgl, int nsge,
-                        uint32_t imm_data, int flags)
+static int rs_write_data(struct rsocket *rs, struct ibv_sge *sge, int flags)
 {
        uint64_t addr;
        uint32_t rkey;
+       uint32_t len = sge->length;
 
        rs->sseq_no++;
        rs->sqe_avail--;
-       rs->sbuf_bytes_avail -= wr_id.length;
+       rs->sbuf_bytes_avail -= len;
 
        addr = rs->target_sgl[rs->target_sge].addr;
        rkey = rs->target_sgl[rs->target_sge].key;
 
-       rs->target_sgl[rs->target_sge].addr += wr_id.length;
-       rs->target_sgl[rs->target_sge].length -= wr_id.length;
+       rs->target_sgl[rs->target_sge].addr += len;
+       rs->target_sgl[rs->target_sge].length -= len;
 
        if (!rs->target_sgl[rs->target_sge].length) {
                if (++rs->target_sge == RS_SGL_SIZE)
                        rs->target_sge = 0;
        }
 
-       return rs_post_write(rs, wr_id.wr_id, sgl, nsge, imm_data, flags, addr, rkey);
+       return rs_post_write(rs, rs_wrid_set(1, len), sge, 1,
+                            rs_msg_set(RS_OP_DATA, len), flags, addr, rkey);
 }
 
 static uint32_t rs_sbuf_left(struct rsocket *rs)
 {
        return (uint32_t) (((uint64_t) (uintptr_t) &rs->sbuf[rs->sbuf_size]) -
-                          rs->ssgl[0].addr);
+                          rs->ssge.addr);
 }
 
 static void rs_send_credits(struct rsocket *rs)
@@ -797,7 +783,6 @@ static void rs_update_credits(struct rsocket *rs)
 static int rs_poll_cq(struct rsocket *rs)
 {
        struct ibv_wc wc;
-       union rs_wr_id *wr_id;
        uint32_t imm_data;
        int ret, rcnt = 0;
 
@@ -827,9 +812,8 @@ static int rs_poll_cq(struct rsocket *rs)
                        }
                } else {
                        if (wc.wr_id) {
-                               wr_id = (union rs_wr_id *) &wc.wr_id;
-                               rs->sqe_avail++; /* += wr_id->sqe_count; */
-                               rs->sbuf_bytes_avail += wr_id->length;
+                               rs->sqe_avail += rs_wrid_sqe(wc.wr_id);
+                               rs->sbuf_bytes_avail += rs_wrid_len(wc.wr_id);
                        } else {
                                rs->ctrl_avail++;
                        }
@@ -1144,34 +1128,22 @@ ssize_t rsend(int socket, const void *buf, size_t len, int flags)
                        xfer_size = rs->sbuf_bytes_avail;
                if (xfer_size > rs->target_sgl[rs->target_sge].length)
                        xfer_size = rs->target_sgl[rs->target_sge].length;
+               if (xfer_size > rs_sbuf_left(rs))
+                       xfer_size = rs_sbuf_left(rs);
 
                if (xfer_size <= rs->sq_inline) {
                        sge.addr = (uintptr_t) buf;
                        sge.length = xfer_size;
                        sge.lkey = 0;
-                       ret = rs_write_data(rs, rs_wrid(1, xfer_size),
-                                           &sge, 1, rs_msg_set(RS_OP_DATA, xfer_size),
-                                           IBV_SEND_INLINE);
-               } else if (xfer_size <= rs_sbuf_left(rs)) {
-                       memcpy((void *) (uintptr_t) rs->ssgl[0].addr, buf, xfer_size);
-                       rs->ssgl[0].length = xfer_size;
-                       ret = rs_write_data(rs, rs_wrid(1, xfer_size),
-                                           rs->ssgl, 1,
-                                           rs_msg_set(RS_OP_DATA, xfer_size), 0);
+                       ret = rs_write_data(rs, &sge, IBV_SEND_INLINE);
+               } else {
+                       memcpy((void *) (uintptr_t) rs->ssge.addr, buf, xfer_size);
+                       rs->ssge.length = xfer_size;
+                       ret = rs_write_data(rs, &rs->ssge, 0);
                        if (xfer_size < rs_sbuf_left(rs))
-                               rs->ssgl[0].addr += xfer_size;
+                               rs->ssge.addr += xfer_size;
                        else
-                               rs->ssgl[0].addr = (uintptr_t) rs->sbuf;
-               } else {
-                       rs->ssgl[0].length = rs_sbuf_left(rs);
-                       memcpy((void *) (uintptr_t) rs->ssgl[0].addr, buf,
-                               rs->ssgl[0].length);
-                       rs->ssgl[1].length = xfer_size - rs->ssgl[0].length;
-                       memcpy(rs->sbuf, buf + rs->ssgl[0].length, rs->ssgl[1].length);
-                       ret = rs_write_data(rs, rs_wrid(1, xfer_size),
-                                           rs->ssgl, 2,
-                                           rs_msg_set(RS_OP_DATA, xfer_size), 0);
-                       rs->ssgl[0].addr = (uintptr_t) rs->sbuf + rs->ssgl[1].length;
+                               rs->ssge.addr = (uintptr_t) rs->sbuf;
                }
                if (ret)
                        break;
@@ -1253,33 +1225,21 @@ static ssize_t rsendv(int socket, const struct iovec *iov, int iovcnt, int flags
                        xfer_size = rs->sbuf_bytes_avail;
                if (xfer_size > rs->target_sgl[rs->target_sge].length)
                        xfer_size = rs->target_sgl[rs->target_sge].length;
-
-               if (xfer_size <= rs_sbuf_left(rs)) {
-                       rs_copy_iov((void *) (uintptr_t) rs->ssgl[0].addr,
-                                   &cur_iov, &offset, xfer_size);
-                       rs->ssgl[0].length = xfer_size;
-                       ret = rs_write_data(rs, rs_wrid(1, xfer_size),
-                                           rs->ssgl, 1,
-                                           rs_msg_set(RS_OP_DATA, xfer_size),
-                                           xfer_size <= rs->sq_inline ? IBV_SEND_INLINE : 0);
-                       if (xfer_size < rs_sbuf_left(rs))
-                               rs->ssgl[0].addr += xfer_size;
-                       else
-                               rs->ssgl[0].addr = (uintptr_t) rs->sbuf;
-               } else {
-                       rs->ssgl[0].length = rs_sbuf_left(rs);
-                       rs_copy_iov((void *) (uintptr_t) rs->ssgl[0].addr, &cur_iov,
-                                   &offset, rs->ssgl[0].length);
-                       rs->ssgl[1].length = xfer_size - rs->ssgl[0].length;
-                       rs_copy_iov(rs->sbuf, &cur_iov, &offset, rs->ssgl[1].length);
-                       ret = rs_write_data(rs, rs_wrid(1, xfer_size),
-                                           rs->ssgl, 2,
-                                           rs_msg_set(RS_OP_DATA, xfer_size),
-                                           xfer_size <= rs->sq_inline ? IBV_SEND_INLINE : 0);
-                       rs->ssgl[0].addr = (uintptr_t) rs->sbuf + rs->ssgl[1].length;
-               }
+               if (xfer_size > rs_sbuf_left(rs))
+                       xfer_size = rs_sbuf_left(rs);
+
+               rs_copy_iov((void *) (uintptr_t) rs->ssge.addr,
+                           &cur_iov, &offset, xfer_size);
+               rs->ssge.length = xfer_size;
+               ret = rs_write_data(rs, &rs->ssge, xfer_size <= rs->sq_inline ?
+                                                  IBV_SEND_INLINE : 0);
                if (ret)
                        break;
+
+               if (xfer_size < rs_sbuf_left(rs))
+                       rs->ssge.addr += xfer_size;
+               else
+                       rs->ssge.addr = (uintptr_t) rs->sbuf;
        }
        fastlock_release(&rs->slock);