From d98b1937768c9f4e4420bd25406e5f0304d224bb Mon Sep 17 00:00:00 2001 From: Ralph Campbell Date: Wed, 16 Apr 2008 21:09:27 -0700 Subject: [PATCH] IB/ipath: Use PIO buffer for RC ACKs This reduces the latency for RC ACKs when a PIO buffer is available. Signed-off-by: Ralph Campbell Signed-off-by: Roland Dreier --- drivers/infiniband/hw/ipath/ipath_rc.c | 57 ++++++++++++++++++-------- 1 file changed, 39 insertions(+), 18 deletions(-) diff --git a/drivers/infiniband/hw/ipath/ipath_rc.c b/drivers/infiniband/hw/ipath/ipath_rc.c index 40f3e37d7a..f765d48464 100644 --- a/drivers/infiniband/hw/ipath/ipath_rc.c +++ b/drivers/infiniband/hw/ipath/ipath_rc.c @@ -31,6 +31,8 @@ * SOFTWARE. */ +#include + #include "ipath_verbs.h" #include "ipath_kernel.h" @@ -585,19 +587,39 @@ bail: static void send_rc_ack(struct ipath_qp *qp) { struct ipath_ibdev *dev = to_idev(qp->ibqp.device); + struct ipath_devdata *dd; u16 lrh0; u32 bth0; u32 hwords; + u32 __iomem *piobuf; struct ipath_ib_header hdr; struct ipath_other_headers *ohdr; unsigned long flags; + spin_lock_irqsave(&qp->s_lock, flags); + /* Don't send ACK or NAK if a RDMA read or atomic is pending. */ if (qp->r_head_ack_queue != qp->s_tail_ack_queue || (qp->s_flags & IPATH_S_ACK_PENDING) || qp->s_ack_state != OP(ACKNOWLEDGE)) goto queue_ack; + spin_unlock_irqrestore(&qp->s_lock, flags); + + dd = dev->dd; + piobuf = ipath_getpiobuf(dd, 0, NULL); + if (!piobuf) { + /* + * We are out of PIO buffers at the moment. + * Pass responsibility for sending the ACK to the + * send tasklet so that when a PIO buffer becomes + * available, the ACK is sent ahead of other outgoing + * packets. + */ + spin_lock_irqsave(&qp->s_lock, flags); + goto queue_ack; + } + /* Construct the header. */ ohdr = &hdr.u.oth; lrh0 = IPATH_LRH_BTH; @@ -611,7 +633,7 @@ static void send_rc_ack(struct ipath_qp *qp) lrh0 = IPATH_LRH_GRH; } /* read pkey_index w/o lock (its atomic) */ - bth0 = ipath_get_pkey(dev->dd, qp->s_pkey_index) | + bth0 = ipath_get_pkey(dd, qp->s_pkey_index) | (OP(ACKNOWLEDGE) << 24) | (1 << 22); if (qp->r_nak_state) ohdr->u.aeth = cpu_to_be32((qp->r_msn & IPATH_MSN_MASK) | @@ -623,30 +645,29 @@ static void send_rc_ack(struct ipath_qp *qp) hdr.lrh[0] = cpu_to_be16(lrh0); hdr.lrh[1] = cpu_to_be16(qp->remote_ah_attr.dlid); hdr.lrh[2] = cpu_to_be16(hwords + SIZE_OF_CRC); - hdr.lrh[3] = cpu_to_be16(dev->dd->ipath_lid); + hdr.lrh[3] = cpu_to_be16(dd->ipath_lid); ohdr->bth[0] = cpu_to_be32(bth0); ohdr->bth[1] = cpu_to_be32(qp->remote_qpn); ohdr->bth[2] = cpu_to_be32(qp->r_ack_psn & IPATH_PSN_MASK); - /* - * If we can send the ACK, clear the ACK state. - */ - if (ipath_verbs_send(qp, &hdr, hwords, NULL, 0) == 0) { - dev->n_unicast_xmit++; - goto done; - } + writeq(hwords + 1, piobuf); - /* - * We are out of PIO buffers at the moment. - * Pass responsibility for sending the ACK to the - * send tasklet so that when a PIO buffer becomes - * available, the ACK is sent ahead of other outgoing - * packets. - */ - dev->n_rc_qacks++; + if (dd->ipath_flags & IPATH_PIO_FLUSH_WC) { + u32 *hdrp = (u32 *) &hdr; + + ipath_flush_wc(); + __iowrite32_copy(piobuf + 2, hdrp, hwords - 1); + ipath_flush_wc(); + __raw_writel(hdrp[hwords - 1], piobuf + hwords + 1); + } else + __iowrite32_copy(piobuf + 2, (u32 *) &hdr, hwords); + + ipath_flush_wc(); + + dev->n_unicast_xmit++; + goto done; queue_ack: - spin_lock_irqsave(&qp->s_lock, flags); dev->n_rc_qacks++; qp->s_flags |= IPATH_S_ACK_PENDING; qp->s_nak_state = qp->r_nak_state; -- 2.39.5