Date: Thu, 14 May 2015 00:21:56 -0700 From: John-Mark Gurney <jmg@funkthat.com> To: Ian Lepore <ian@freebsd.org> Cc: Adrian Chadd <adrian@freebsd.org>, Hans Petter Selasky <hps@selasky.org>, David Chisnall <theraven@freebsd.org>, Poul-Henning Kamp <phk@phk.freebsd.dk>, Baptiste Daroussin <bapt@freebsd.org>, "current@freebsd.org" <current@freebsd.org> Subject: Re: Increase BUFSIZ to 8192 Message-ID: <20150514072155.GT37063@funkthat.com> In-Reply-To: <1431542835.1221.30.camel@freebsd.org> References: <20150511230635.GA46991@ivaldir.etoilebsd.net> <20150512032307.GP37063@funkthat.com> <14994.1431412293@critter.freebsd.dk> <20150513080342.GE37063@funkthat.com> <A1224018-7540-4C76-91EF-AEA2655E49A8@FreeBSD.org> <55530CC3.1090204@selasky.org> <1431528249.1221.15.camel@freebsd.org> <CAJ-VmonL9mT4JLqfSefKYiwv5-ecLkx9RZ5=kXt__%2Bs9iO4%2B9Q@mail.gmail.com> <20150513181347.GM37063@funkthat.com> <1431542835.1221.30.camel@freebsd.org>
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Ian Lepore wrote this message on Wed, May 13, 2015 at 12:47 -0600:
> On Wed, 2015-05-13 at 11:13 -0700, John-Mark Gurney wrote:
> > Adrian Chadd wrote this message on Wed, May 13, 2015 at 08:34 -0700:
> > > The reason I ask about "why is it faster?" is because for embedded-y
> > > things with low RAM we may not want that to happen due to memory
> > > constraints. However, we may actually want to do some form of
> > > autotuning on some platforms.
> >
> > If you're already running a program, the difference between 1k and
> > 8k isn't significant... I'll give you 64k can be significant for
> > embedded-y platforms... But this goes back to the, we need a global
> > knob saying I want low memory usage, and I am willing to pay for it
> > in performance...
>
> It is NOT just a difference of 1K vs 8K. It's that much times however
> many BUFSIZ-sized things a program has allocated at once. It's where
> they are allocated. As I've already pointed out, BUFSIZ appears in the
> base code over 2000 times. Where is the analysis of the impact an 8x
> change is going to have on all those uses?
Since you apprently missed my original reply, I said that we shouldn't
abuse BUFSIZ for this work, and that it should be changed in mdXhl.c...
I agree that changing this size to effect all the other files is ill
advised and should not be done...
--
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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