staging/rdma/hfi1: add ACK coalescing logic
Implement ACK coalesing logic using a 8 bit counter.
The algorithm is send pio ack when:
- fecn present
- this is the first packet in an interrupt session
- counter is >= HFI1_PSN_CREDIT
Otherwise the ack is defered.
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/staging/rdma/hfi1/rc.c b/drivers/staging/rdma/hfi1/rc.c
index 0c10012..6f4a155 100644
--- a/drivers/staging/rdma/hfi1/rc.c
+++ b/drivers/staging/rdma/hfi1/rc.c
@@ -1618,6 +1618,17 @@
}
}
+static inline void rc_cancel_ack(struct hfi1_qp *qp)
+{
+ qp->r_adefered = 0;
+ if (list_empty(&qp->rspwait))
+ return;
+ list_del_init(&qp->rspwait);
+ qp->r_flags &= ~HFI1_R_RSP_DEFERED_ACK;
+ if (atomic_dec_and_test(&qp->refcount))
+ wake_up(&qp->wait);
+}
+
/**
* rc_rcv_error - process an incoming duplicate or error RC packet
* @ohdr: the other headers for this packet
@@ -2335,8 +2346,22 @@
qp->r_ack_psn = psn;
qp->r_nak_state = 0;
/* Send an ACK if requested or required. */
- if (psn & (1 << 31))
- goto send_ack;
+ if (psn & IB_BTH_REQ_ACK) {
+ if (packet->numpkt == 0) {
+ rc_cancel_ack(qp);
+ goto send_ack;
+ }
+ if (qp->r_adefered >= HFI1_PSN_CREDIT) {
+ rc_cancel_ack(qp);
+ goto send_ack;
+ }
+ if (unlikely(is_fecn)) {
+ rc_cancel_ack(qp);
+ goto send_ack;
+ }
+ qp->r_adefered++;
+ rc_defered_ack(rcd, qp);
+ }
return;
rnr_nak: