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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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