> I apologize, I've been swamped and just pushed this one out the door.
> I guess, though, everyone here is always swamped -- I'll put in the
> extra little bit of effort and do things properly next time.
It's not just you, but I wish everyone would just take the time to set
things up once and for all (and possibly learn how to use automation
such as git-send-email) so that I don't have to keep editing trivial
things in nearly every patch I get. It doesn't take any longer to send
a patch that automated tools can handle -- you just have to care enough
to learn how to do it.
> this is in the data path, so I put in a lot of effort to guarantee that
> there would not be an extra "if" for ALL post_sends. This way, although
> a bit ugly, only LSO packets are affected, and there is no extra "if".
Yeah, I figured that was what you wanted to do. But I'm not convinced
that the bigger I-cache footprint of duplicating code doesn't hurt more
than a single conditional branch. Anyway, what about doing something
like the below (the cost now becomes two more assignments):
diff --git a/drivers/infiniband/hw/mlx4/qp.c b/drivers/infiniband/hw/mlx4/qp.c
index 39167a7..2d8ae4c 100644
--- a/drivers/infiniband/hw/mlx4/qp.c
+++ b/drivers/infiniband/hw/mlx4/qp.c
@@ -1462,7 +1462,8 @@ static void __set_data_seg(struct mlx4_wqe_data_seg
*dseg, struct ib_sge *sg)
}
static int build_lso_seg(struct mlx4_wqe_lso_seg *wqe, struct ib_send_wr *wr,
- struct mlx4_ib_qp *qp, unsigned *lso_seg_len)
+ struct mlx4_ib_qp *qp, unsigned *lso_seg_len,
+ __be32 *lso_hdr_sz)
{
unsigned halign = ALIGN(sizeof *wqe + wr->wr.ud.hlen, 16);
@@ -1479,12 +1480,8 @@ static int build_lso_seg(struct mlx4_wqe_lso_seg *wqe,
struct ib_send_wr *wr,
memcpy(wqe->header, wr->wr.ud.header, wr->wr.ud.hlen);
- /* make sure LSO header is written before overwriting stamping */
- wmb();
-
- wqe->mss_hdr_size = cpu_to_be32((wr->wr.ud.mss - wr->wr.ud.hlen) << 16 |
- wr->wr.ud.hlen);
-
+ *lso_hdr_sz = cpu_to_be32((wr->wr.ud.mss - wr->wr.ud.hlen) << 16 |
+ wr->wr.ud.hlen);
*lso_seg_len = halign;
return 0;
}
@@ -1518,6 +1515,9 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct
ib_send_wr *wr,
int uninitialized_var(stamp);
int uninitialized_var(size);
unsigned uninitialized_var(seglen);
+ __be32 *lso_wqe;
+ __be32 uninitialized_var(lso_hdr_sz);
+ __be32 dummy;
int i;
spin_lock_irqsave(&qp->sq.lock, flags);
@@ -1525,6 +1525,8 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct
ib_send_wr *wr,
ind = qp->sq_next_wqe;
for (nreq = 0; wr; ++nreq, wr = wr->next) {
+ lso_wqe = &dummy;
+
if (mlx4_wq_overflow(&qp->sq, nreq, qp->ibqp.send_cq)) {
err = -ENOMEM;
*bad_wr = wr;
@@ -1606,11 +1608,12 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct
ib_send_wr *wr,
size += sizeof (struct mlx4_wqe_datagram_seg) / 16;
if (wr->opcode == IB_WR_LSO) {
- err = build_lso_seg(wqe, wr, qp, &seglen);
+ err = build_lso_seg(wqe, wr, qp, &seglen,
&lso_hdr_sz);
if (unlikely(err)) {
*bad_wr = wr;
goto out;
}
+ lso_wqe = (__be32 *) wqe;
wqe += seglen;
size += seglen / 16;
}
@@ -1652,6 +1655,13 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct
ib_send_wr *wr,
for (i = wr->num_sge - 1; i >= 0; --i, --dseg)
set_data_seg(dseg, wr->sg_list + i);
+ /*
+ * Possibly overwrite stamping in cacheline with LSO
+ * segment only after making sure all data segments
+ * are written.
+ */
+ *lso_wqe = lso_hdr_sz;
+
ctrl->fence_size = (wr->send_flags & IB_SEND_FENCE ?
MLX4_WQE_CTRL_FENCE : 0) | size;
_______________________________________________
general mailing list
[email protected]
http://lists.openfabrics.org/cgi-bin/mailman/listinfo/general
To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
