On Thu, 2007-01-04 at 13:34 -0800, Roland Dreier wrote: > OK, I'm back from vacation today. > > Anyway I don't have a definitive statement on this right now. I guess > I agree that I don't like having an extra parameter to a function that > should be pretty fast (although req notify isn't quite as hot as > something like posting a send request or polling a cq), given that it > adds measurable overhead. (And I am surprised that the overhead is > measurable, since 3 arguments still fit in registers, but OK). > > I also agree that adding an extra entry point just to pass in the user > data is ugly, and also racy. > > Giving the kernel driver a pointer it can read seems OK I guess, > although it's a little ugly to have a backdoor channel like that. > > I'm somewhat surprised the driver has to go into the kernel to rearm a > CQ -- what makes the operation need kernel privileges? (Sorry for not > reading the code) > -
Rearming the CQ requires reading and writing to a global adapter register that is shared and thus needs to be protected. They didn't architect the rearm to be a direct user operation. Steve. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
