Date: Tue, 4 Sep 2012 20:06:59 -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-VmonCguhTxNqW2qeCPAOnGn8e_73p6mwZThdrCSmfw9TCfg@mail.gmail.com> In-Reply-To: <1346803062.59094.27.camel@revolution.hippie.lan> References: <1346777897.1140.633.camel@revolution.hippie.lan> <CAJ-VmonnaPE=6SVvc1hDE2URAY9TSWkMXOwa7F4X2knBQgbxNw@mail.gmail.com> <1346803062.59094.27.camel@revolution.hippie.lan>
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I just want to make sure that you don't assume individual memory access costs are the same regardless of how big the allocations are. Ie, if you have a bunch of scattered L1-sized allocations, versus them all being nearby in the same 512/1024 byte page; the underlying memory architecture may be doing memory transactions at a slightly larger size than your L1 assumption. Damn these hierarchicial memory systems. Adrian
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