[openib-general] [PATCH] (fixed) reduce qp locking on cq poll

[Roland Dreier]

    Michael> Locking during the poll cq operation can be reduced, by
    Michael> locking the cq while qp is being removed from the qp
    Michael> array.  This also avoids an extra atomic operation for
    Michael> reference counting.

Look reasonable.  Can you resend with /* */ comments instead of //?

    Michael> TODO implies the same can be done for cqs, but I dont see
    Michael> how, since we dont take a lock on eq, so this I have left
    Michael> in the TODO.  This works but I dont have the fast
    Michael> hardware to check the speed effect.

We would have to add a lock to the EQ to do the same for CQs.  However
this would save both the CQ table lock and the atomic reference
counting of the CQ so it should be a net win.

I'm a little worried that you see no improvement from this patch -- it
doesn't seem like fast hardware should be required.

 - R.