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Commit 84172dee authored by Steve Wise's avatar Steve Wise Committed by Roland Dreier
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RDMA/cxgb4: Optimize CQ overflow detection 



1) save the timestamp flit in the cq when we consume a CQE.

2) always compare the saved flit with the previous entry flit when
   reading the next CQE entry.  If the flits don't compare, then we
   have overflowed.

Signed-off-by: default avatarSteve Wise <swise@opengridcomputing.com>
Signed-off-by: default avatarRoland Dreier <rolandd@cisco.com>
parent 895cf5f3

drivers/infiniband/hw/cxgb4/cq.c

+1 −0
Original line number Diff line number Diff line
@@ -373,6 +373,7 @@ static void create_read_req_cqe(struct t4_wq *wq, struct t4_cqe *hw_cqe, 
				 V_CQE_SWCQE(SW_CQE(hw_cqe)) |

				 V_CQE_OPCODE(FW_RI_READ_REQ) |

				 V_CQE_TYPE(1));

	read_cqe->bits_type_ts = hw_cqe->bits_type_ts;

}



/*

drivers/infiniband/hw/cxgb4/t4.h

+16 −12
Original line number Diff line number Diff line
@@ -434,7 +434,7 @@ struct t4_cq { 
	struct c4iw_rdev *rdev;

	u64 ugts;

	size_t memsize;

	u64 timestamp;

	__be64 bits_type_ts;

	u32 cqid;

	u16 size; /* including status page */

	u16 cidx;
@@ -487,6 +487,7 @@ static inline void t4_swcq_consume(struct t4_cq *cq) 


static inline void t4_hwcq_consume(struct t4_cq *cq)

{

	cq->bits_type_ts = cq->queue[cq->cidx].bits_type_ts;

	cq->cidx_inc++;

	if (++cq->cidx == cq->size) {

		cq->cidx = 0;
@@ -501,20 +502,23 @@ static inline int t4_valid_cqe(struct t4_cq *cq, struct t4_cqe *cqe) 


static inline int t4_next_hw_cqe(struct t4_cq *cq, struct t4_cqe **cqe)

{

	int ret = 0;

	u64 bits_type_ts = be64_to_cpu(cq->queue[cq->cidx].bits_type_ts);

	int ret;

	u16 prev_cidx;



	if (G_CQE_GENBIT(bits_type_ts) == cq->gen) {

		*cqe = &cq->queue[cq->cidx];

		cq->timestamp = G_CQE_TS(bits_type_ts);

	} else if (G_CQE_TS(bits_type_ts) > cq->timestamp)

		ret = -EOVERFLOW;

	if (cq->cidx == 0)

		prev_cidx = cq->size - 1;

	else

		ret = -ENODATA;

	if (ret == -EOVERFLOW) {

		printk(KERN_ERR MOD "cq overflow cqid %u\n", cq->cqid);

		prev_cidx = cq->cidx - 1;



	if (cq->queue[prev_cidx].bits_type_ts != cq->bits_type_ts) {

		ret = -EOVERFLOW;

		cq->error = 1;

	}

		printk(KERN_ERR MOD "cq overflow cqid %u\n", cq->cqid);

	} else if (t4_valid_cqe(cq, &cq->queue[cq->cidx])) {

		*cqe = &cq->queue[cq->cidx];

		ret = 0;

	} else

		ret = -ENODATA;

	return ret;

}