[openib-general] Re: [PATCH 1 of 2] mthca: qp size calculations

Roland Dreier rolandd at cisco.com
Tue Nov 8 13:44:57 PST 2005


Thanks, this looks pretty good.  I updated the computation of the WQE
sizes to be more accurate (I hope).  We know that a bind request will
not have any s/g entries, and an atomic request will have only one s/g
entry, so we don't have to add together all of our worst cases.

Since this is bumping the uverbs ABI anyway, I also took the
opportunity to get rid of the max_sge member in the modify SRQ
command.  It's not a valid parameter, so there's no reason to pass it
from userspace.

Comments?

--- infiniband/include/rdma/ib_user_verbs.h	(revision 3989)
+++ infiniband/include/rdma/ib_user_verbs.h	(working copy)
@@ -43,7 +43,7 @@
  * Increment this value if any changes that break userspace ABI
  * compatibility are made.
  */
-#define IB_USER_VERBS_ABI_VERSION	3
+#define IB_USER_VERBS_ABI_VERSION	4
 
 enum {
 	IB_USER_VERBS_CMD_GET_CONTEXT,
@@ -333,6 +333,11 @@ struct ib_uverbs_create_qp {
 struct ib_uverbs_create_qp_resp {
 	__u32 qp_handle;
 	__u32 qpn;
+	__u32 max_send_wr;
+	__u32 max_recv_wr;
+	__u32 max_send_sge;
+	__u32 max_recv_sge;
+	__u32 max_inline_data;
 };
 
 /*
@@ -552,9 +557,7 @@ struct ib_uverbs_modify_srq {
 	__u32 srq_handle;
 	__u32 attr_mask;
 	__u32 max_wr;
-	__u32 max_sge;
 	__u32 srq_limit;
-	__u32 reserved;
 	__u64 driver_data[0];
 };
 
--- infiniband/core/uverbs_cmd.c	(revision 3989)
+++ infiniband/core/uverbs_cmd.c	(working copy)
@@ -908,7 +908,12 @@ retry:
 	if (ret)
 		goto err_destroy;
 
-	resp.qp_handle = uobj->uobject.id;
+	resp.qp_handle       = uobj->uobject.id;
+	resp.max_recv_sge    = attr.cap.max_recv_sge;
+	resp.max_send_sge    = attr.cap.max_send_sge;
+	resp.max_recv_wr     = attr.cap.max_recv_wr;
+	resp.max_send_wr     = attr.cap.max_send_wr;
+	resp.max_inline_data = attr.cap.max_inline_data;
 
 	if (copy_to_user((void __user *) (unsigned long) cmd.response,
 			 &resp, sizeof resp)) {
@@ -1701,7 +1706,6 @@ ssize_t ib_uverbs_modify_srq(struct ib_u
 	}
 
 	attr.max_wr    = cmd.max_wr;
-	attr.max_sge   = cmd.max_sge;
 	attr.srq_limit = cmd.srq_limit;
 
 	ret = ib_modify_srq(srq, &attr, cmd.attr_mask);
--- infiniband/hw/mthca/mthca_provider.c	(revision 3989)
+++ infiniband/hw/mthca/mthca_provider.c	(working copy)
@@ -604,11 +604,11 @@ static struct ib_qp *mthca_create_qp(str
 		return ERR_PTR(err);
 	}
 
-	init_attr->cap.max_inline_data = 0;
 	init_attr->cap.max_send_wr     = qp->sq.max;
 	init_attr->cap.max_recv_wr     = qp->rq.max;
 	init_attr->cap.max_send_sge    = qp->sq.max_gs;
 	init_attr->cap.max_recv_sge    = qp->rq.max_gs;
+	init_attr->cap.max_inline_data = qp->max_inline_data;
 
 	return &qp->ibqp;
 }
--- infiniband/hw/mthca/mthca_provider.h	(revision 3989)
+++ infiniband/hw/mthca/mthca_provider.h	(working copy)
@@ -251,6 +251,7 @@ struct mthca_qp {
 	struct mthca_wq        sq;
 	enum ib_sig_type       sq_policy;
 	int                    send_wqe_offset;
+	int                    max_inline_data;
 
 	u64                   *wrid;
 	union mthca_buf	       queue;
--- infiniband/hw/mthca/mthca_cmd.c	(revision 3989)
+++ infiniband/hw/mthca/mthca_cmd.c	(working copy)
@@ -1060,6 +1060,8 @@ int mthca_QUERY_DEV_LIM(struct mthca_dev
 		dev_lim->hca.arbel.resize_srq = field & 1;
 		MTHCA_GET(field, outbox, QUERY_DEV_LIM_MAX_SG_RQ_OFFSET);
 		dev_lim->max_sg = min_t(int, field, dev_lim->max_sg);
+		MTHCA_GET(size, outbox, QUERY_DEV_LIM_MAX_DESC_SZ_RQ_OFFSET);
+		dev_lim->max_desc_sz = min_t(int, size, dev_lim->max_desc_sz);
 		MTHCA_GET(size, outbox, QUERY_DEV_LIM_MPT_ENTRY_SZ_OFFSET);
 		dev_lim->mpt_entry_sz = size;
 		MTHCA_GET(field, outbox, QUERY_DEV_LIM_PBL_SZ_OFFSET);
--- infiniband/hw/mthca/mthca_dev.h	(revision 3989)
+++ infiniband/hw/mthca/mthca_dev.h	(working copy)
@@ -131,6 +131,7 @@ struct mthca_limits {
 	int      max_sg;
 	int      num_qps;
 	int      max_wqes;
+	int	 max_desc_sz;
 	int	 max_qp_init_rdma;
 	int      reserved_qps;
 	int      num_srqs;
--- infiniband/hw/mthca/mthca_main.c	(revision 3989)
+++ infiniband/hw/mthca/mthca_main.c	(working copy)
@@ -168,6 +168,7 @@ static int __devinit mthca_dev_lim(struc
 	mdev->limits.max_srq_wqes       = dev_lim->max_srq_sz;
 	mdev->limits.reserved_srqs      = dev_lim->reserved_srqs;
 	mdev->limits.reserved_eecs      = dev_lim->reserved_eecs;
+	mdev->limits.max_desc_sz        = dev_lim->max_desc_sz;
 	/*
 	 * Subtract 1 from the limit because we need to allocate a
 	 * spare CQE so the HCA HW can tell the difference between an
--- infiniband/hw/mthca/mthca_qp.c	(revision 3989)
+++ infiniband/hw/mthca/mthca_qp.c	(working copy)
@@ -883,6 +883,48 @@ int mthca_modify_qp(struct ib_qp *ibqp, 
 	return err;
 }
 
+static void mthca_adjust_qp_caps(struct mthca_dev *dev,
+				 struct mthca_pd *pd,
+				 struct mthca_qp *qp)
+{
+	int max_data_size;
+
+	/*
+	 * Calculate the maximum size of WQE s/g segments, excluding
+	 * the next segment and other non-data segments.
+	 */
+	max_data_size = min(dev->limits.max_desc_sz, 1 << qp->sq.wqe_shift) -
+		sizeof (struct mthca_next_seg);
+
+	switch (qp->transport) {
+	case MLX:
+		max_data_size -= 2 * sizeof (struct mthca_data_seg);
+		break;
+
+	case UD:
+		if (mthca_is_memfree(dev))
+			max_data_size -= sizeof (struct mthca_arbel_ud_seg);
+		else
+			max_data_size -= sizeof (struct mthca_tavor_ud_seg);
+		break;
+
+	default:
+		max_data_size -= sizeof (struct mthca_raddr_seg);
+		break;
+	}
+
+	/* We don't support inline data for kernel QPs (yet). */
+	if (!pd->ibpd.uobject)
+		qp->max_inline_data = 0;
+        else
+		qp->max_inline_data = max_data_size - MTHCA_INLINE_HEADER_SIZE;
+
+	qp->sq.max_gs = max_data_size / sizeof (struct mthca_data_seg);
+	qp->rq.max_gs = (min(dev->limits.max_desc_sz, 1 << qp->rq.wqe_shift) -
+			sizeof (struct mthca_next_seg)) /
+			sizeof (struct mthca_data_seg);
+}
+
 /*
  * Allocate and register buffer for WQEs.  qp->rq.max, sq.max,
  * rq.max_gs and sq.max_gs must all be assigned.
@@ -900,27 +942,53 @@ static int mthca_alloc_wqe_buf(struct mt
 	size = sizeof (struct mthca_next_seg) +
 		qp->rq.max_gs * sizeof (struct mthca_data_seg);
 
+	if (size > dev->limits.max_desc_sz)
+		return -EINVAL;
+
 	for (qp->rq.wqe_shift = 6; 1 << qp->rq.wqe_shift < size;
 	     qp->rq.wqe_shift++)
 		; /* nothing */
 
-	size = sizeof (struct mthca_next_seg) +
-		qp->sq.max_gs * sizeof (struct mthca_data_seg);
+	size = qp->sq.max_gs * sizeof (struct mthca_data_seg);
 	switch (qp->transport) {
 	case MLX:
 		size += 2 * sizeof (struct mthca_data_seg);
 		break;
+
 	case UD:
-		if (mthca_is_memfree(dev))
-			size += sizeof (struct mthca_arbel_ud_seg);
-		else
-			size += sizeof (struct mthca_tavor_ud_seg);
+		size += mthca_is_memfree(dev) ?
+			sizeof (struct mthca_arbel_ud_seg) :
+			sizeof (struct mthca_tavor_ud_seg);
+		break;
+
+	case UC:
+		size += sizeof (struct mthca_raddr_seg);
+		break;
+
+	case RC:
+		size += sizeof (struct mthca_raddr_seg);
+		/*
+		 * An atomic op will require an atomic segment, a
+		 * remote address segment and one scatter entry.
+		 */
+		size = max_t(int, size,
+			     sizeof (struct mthca_atomic_seg) +
+			     sizeof (struct mthca_raddr_seg) +
+			     sizeof (struct mthca_data_seg));
 		break;
+
 	default:
-		/* bind seg is as big as atomic + raddr segs */
-		size += sizeof (struct mthca_bind_seg);
+		break;
 	}
 
+	/* Make sure that we have enough space for a bind request */
+	size = max_t(int, size, sizeof (struct mthca_bind_seg));
+
+	size += sizeof (struct mthca_next_seg);
+
+	if (size > dev->limits.max_desc_sz)
+		return -EINVAL;
+
 	for (qp->sq.wqe_shift = 6; 1 << qp->sq.wqe_shift < size;
 	     qp->sq.wqe_shift++)
 		; /* nothing */
@@ -1064,6 +1132,8 @@ static int mthca_alloc_qp_common(struct 
 		return ret;
 	}
 
+	mthca_adjust_qp_caps(dev, pd, qp);
+
 	/*
 	 * If this is a userspace QP, we're done now.  The doorbells
 	 * will be allocated and buffers will be initialized in



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