Date: Thu, 13 Feb 2014 10:07:36 -0800 From: John-Mark Gurney <jmg@funkthat.com> To: Garrett Wollman <wollman@bimajority.org> Cc: FreeBSD Net <freebsd-net@freebsd.org> Subject: Re: Use of contiguous physical memory in cxgbe driver Message-ID: <20140213180736.GA34851@funkthat.com> In-Reply-To: <21245.1163.754141.154430@hergotha.csail.mit.edu> References: <21216.22944.314697.179039@hergotha.csail.mit.edu> <201402111348.52135.jhb@freebsd.org> <CAJ-VmonCdNQPUCQwm0OhqQ3Kt_7x6-g-JwGVZQfzWTgrDYfmqw@mail.gmail.com> <201402121446.19278.jhb@freebsd.org> <21244.20212.423983.960018@hergotha.csail.mit.edu> <20140213075651.GY34851@funkthat.com> <21245.1163.754141.154430@hergotha.csail.mit.edu>
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Garrett Wollman wrote this message on Thu, Feb 13, 2014 at 12:44 -0500:
> <<On Wed, 12 Feb 2014 23:56:51 -0800, John-Mark Gurney <jmg@funkthat.com> said:
>
> > Though we might want to keep a few mbufs reserved for receive now that
> > you mention it... We should never get to the point where we can't
> > allocate even one frame for receive...
>
> It's very easy to get to that state if the driver insists on getting
> three physically contiguous pages (which is what it takes to allocate
> a single 9k cluster)
Well, if you're using a cheap NIC that can't do scatter/gather DMA,
then you get what you pay for...
--
John-Mark Gurney Voice: +1 415 225 5579
"All that I will do, has been done, All that I have, has not."
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