Date: Wed, 30 Aug 2006 11:18:43 -0700 From: "Jack Vogel" <jfvogel@gmail.com> To: "Andrew Gallatin" <gallatin@cs.duke.edu> Cc: freebsd-net <freebsd-net@freebsd.org>, Alan Cox <alc@cs.rice.edu>, freebsd-current <freebsd-current@freebsd.org>, Mohan Srinivasan <mohan_srinivasan@yahoo.com>, Robert Watson <rwatson@freebsd.org> Subject: Re: RFC: FreeBSD I/OAT driver Message-ID: <2a41acea0608301118r3c9bcces1c5b20fe208d6e93@mail.gmail.com> In-Reply-To: <17653.51598.910897.127606@grasshopper.cs.duke.edu> References: <2a41acea0608291624u4ee91cdej2d87aa19e2e5ba62@mail.gmail.com> <17653.51598.910897.127606@grasshopper.cs.duke.edu>
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On 8/30/06, Andrew Gallatin <gallatin@cs.duke.edu> wrote: > > Excellent! Can you share some of these results? I would love to try > it, but I don't have FreeBSD on any machine with I/OAT hardware. Prafulla had the results <nudges Prafulla> > I've taken a very quick look at it. Maybe I'm just being dense, > but I don't like the name "dma_" being in the global namespace. > Maybe things (like dma_*_list should be called at least > dmaengine_*_list, etc. I have no commitment to specifics in the namespace, so it can be changed to suit tastes. > There are some style(9) defects which I'm sure others who are more > proficient at style(9) than I am will point out (// comments, function > names not starting in column 0, etc). Same as above, minor things we can fix... > How deep would you expect so->dma_wait_queue to get? Would it make > sense to keep a pointer to the last item so that insertion is O(1), > rather than O(N)? Again, this is Prafulla's code, he should respond. > Would it be possible to have a sysctl tunable threshold, below which > the system does a normal uiomove? A normal copyout() will certainly > be faster at some point.. This sounds like a good idea. We only provided the stack client, because of interest by a specific customer, but there is potential for this engine to be used in a variety of places, for instance in VM. For more diverse usages the registration/client code would need to be enhanced, something like what Linux has now. That is doable later down the path... > Thanks for the great work! > > Drew Thanks for looking it over :) Jack
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