Date: Tue, 4 Sep 2012 15:37:23 -0700 From: Adrian Chadd <adrian@freebsd.org> To: Ian Lepore <freebsd@damnhippie.dyndns.org> Cc: freebsd-arm@freebsd.org, freebsd-mips@freebsd.org Subject: Re: busdma buffer management enhancements - call for review and test Message-ID: <CAJ-VmonnaPE=6SVvc1hDE2URAY9TSWkMXOwa7F4X2knBQgbxNw@mail.gmail.com> In-Reply-To: <1346777897.1140.633.camel@revolution.hippie.lan> References: <1346777897.1140.633.camel@revolution.hippie.lan>
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Hiya, This is pretty neat work. :) But by converting drivers to use individual uma allocations, aren't you risking fragmenting FIFO rings and such? I'm sure there are platforms out there whose memory controllers operate on minimum sized bits (say, 512 byte chunks for some intel PC chipsets, if I'm not mistaken) .. right now ath(4)'s RX descriptors are almost always kept in order of allocation, but with your proposal it's quite possible they'll be spread all around the the (fixed size) UMA slab. I can't help but think there's some larger scale issues here that are slightly orthogonal to the requirements of (small) embedded platforms. Adrian
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