[openib-general] [PATCH] rcu for event speedup

[Roland Dreier]

    Michael> Hi!  The following patch adds an option to avoid taking
    Michael> the cq table lock on data path, by using RCU.  When
    Michael> enabled, this gets a nice speedup (about 4%) in IP over
    Michael> IB on my hardware.

I don't think this requires using RCU, since you're not really using
anything from rcupdate.h except synchronize_kernel(), and even that is
unnecessary.  I think this could be made a lot simpler by just using
explicit memory barriers and synchronize_irq().  That should also
remove the problem with slowing down the free operation so that this
doesn't need to be made conditional.

(By the way, did you hand edit the patch?  There's no filename header
between the Kconfig chunk and the mthca_cq.c chunks, so the patch
won't apply)

 - R.