>>>>> "Michael" == Michael S Tsirkin <[EMAIL PROTECTED]> writes:
Michael> The following patch avoids taking the cq table lock on
Michael> data path. This gets a nice speedup (about 4%) in IP
Michael> over IB on my hardware.
Michael> Signed-off-by: Michael S. Tsirkin <[EMAIL PROTECTED]>
Thanks...
After thinking about this some more, I don't think we need the
read_barrier_depends() (since free_cq will wait until the interrupt
handler is done before it changes the contents of the cq pointer), and
we don't need the wmb() before the synchronize_irq(), since
spin_unlock has an implied memory barrier.
So this is what I committed:
Index: hw/mthca/mthca_cq.c
===================================================================
--- hw/mthca/mthca_cq.c (revision 1658)
+++ hw/mthca/mthca_cq.c (working copy)
@@ -181,11 +181,7 @@ void mthca_cq_event(struct mthca_dev *de
{
struct mthca_cq *cq;
- spin_lock(&dev->cq_table.lock);
cq = mthca_array_get(&dev->cq_table.cq, cqn & (dev->limits.num_cqs -
1));
- if (cq)
- atomic_inc(&cq->refcount);
- spin_unlock(&dev->cq_table.lock);
if (!cq) {
mthca_warn(dev, "Completion event for bogus CQ %08x\n", cqn);
@@ -193,9 +189,6 @@ void mthca_cq_event(struct mthca_dev *de
}
cq->ibcq.comp_handler(&cq->ibcq, cq->ibcq.cq_context);
-
- if (atomic_dec_and_test(&cq->refcount))
- wake_up(&cq->wait);
}
void mthca_cq_clean(struct mthca_dev *dev, u32 cqn, u32 qpn)
@@ -785,6 +778,11 @@ void mthca_free_cq(struct mthca_dev *dev
cq->cqn & (dev->limits.num_cqs - 1));
spin_unlock_irq(&dev->cq_table.lock);
+ if (dev->mthca_flags & MTHCA_FLAG_MSI_X)
+ synchronize_irq(dev->eq_table.eq[MTHCA_EQ_COMP].msi_x_vector);
+ else
+ synchronize_irq(dev->pdev->irq);
+
atomic_dec(&cq->refcount);
wait_event(cq->wait, !atomic_read(&cq->refcount));
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