staging/rdma/hfi1: Allow a fair scheduling of QPs

This patch fixes the fairness issues in QP scheduling
- the timeout for cond_resched is changed to a ratio of
qp->timeout_jiffies
- workqueue_congested is used to determine if qp needs to
reschedule itself

Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Vennila Megavannan <vennila.megavannan@intel.com>
Signed-off-by: Jubin John <jubin.john@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

diff --git a/drivers/staging/rdma/hfi1/ruc.c b/drivers/staging/rdma/hfi1/ruc.c
index ae28b85..f09badb 100644 (file)
--- a/drivers/staging/rdma/hfi1/ruc.c
+++ b/drivers/staging/rdma/hfi1/ruc.c
@@ -822,29 +822,42 @@ void _hfi1_do_send(struct work_struct *work)
 void hfi1_do_send(struct rvt_qp *qp)
 {
        struct hfi1_pkt_state ps;
+       struct hfi1_qp_priv *priv = qp->priv;
        int (*make_req)(struct rvt_qp *qp);
        unsigned long flags;
        unsigned long timeout;
+       unsigned long timeout_int;
+       int cpu;
 
        ps.dev = to_idev(qp->ibqp.device);
        ps.ibp = to_iport(qp->ibqp.device, qp->port_num);
        ps.ppd = ppd_from_ibp(ps.ibp);
 
-       if ((qp->ibqp.qp_type == IB_QPT_RC ||
-            qp->ibqp.qp_type == IB_QPT_UC) &&
-           !loopback &&
-           (qp->remote_ah_attr.dlid & ~((1 << ps.ppd->lmc) - 1)) ==
-           ps.ppd->lid) {
-               ruc_loopback(qp);
-               return;
-       }
-
-       if (qp->ibqp.qp_type == IB_QPT_RC)
+       switch (qp->ibqp.qp_type) {
+       case IB_QPT_RC:
+               if (!loopback && ((qp->remote_ah_attr.dlid & ~((1 << ps.ppd->lmc
+                                                               ) - 1)) ==
+                                ps.ppd->lid)) {
+                       ruc_loopback(qp);
+                       return;
+               }
                make_req = hfi1_make_rc_req;
-       else if (qp->ibqp.qp_type == IB_QPT_UC)
+               timeout_int = (qp->timeout_jiffies);
+               break;
+       case IB_QPT_UC:
+               if (!loopback && ((qp->remote_ah_attr.dlid & ~((1 << ps.ppd->lmc
+                                                               ) - 1)) ==
+                                ps.ppd->lid)) {
+                       ruc_loopback(qp);
+                       return;
+               }
                make_req = hfi1_make_uc_req;
-       else
+               timeout_int = SEND_RESCHED_TIMEOUT;
+               break;
+       default:
                make_req = hfi1_make_ud_req;
+               timeout_int = SEND_RESCHED_TIMEOUT;
+       }
 
        spin_lock_irqsave(&qp->s_lock, flags);
 
@@ -858,7 +871,9 @@ void hfi1_do_send(struct rvt_qp *qp)
 
        spin_unlock_irqrestore(&qp->s_lock, flags);
 
-       timeout = jiffies + SEND_RESCHED_TIMEOUT;
+       timeout = jiffies + (timeout_int) / 8;
+       cpu = priv->s_sde ? priv->s_sde->cpu :
+                       cpumask_first(cpumask_of_node(ps.ppd->dd->node));
        do {
                /* Check for a constructed packet to be sent. */
                if (qp->s_hdrwords != 0) {
@@ -874,9 +889,18 @@ void hfi1_do_send(struct rvt_qp *qp)
 
                /* allow other tasks to run */
                if (unlikely(time_after(jiffies, timeout))) {
+                       if (workqueue_congested(cpu, ps.ppd->hfi1_wq)) {
+                               spin_lock_irqsave(&qp->s_lock, flags);
+                               qp->s_flags &= ~RVT_S_BUSY;
+                               hfi1_schedule_send(qp);
+                               spin_unlock_irqrestore(&qp->s_lock,
+                                                      flags);
+                               this_cpu_inc(*ps.ppd->dd->send_schedule);
+                               return;
+                       }
                        cond_resched();
                        this_cpu_inc(*ps.ppd->dd->send_schedule);
-                       timeout = jiffies + SEND_RESCHED_TIMEOUT;
+                       timeout = jiffies + (timeout_int) / 8;
                }
        } while (make_req(qp));
 }