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Date:      Tue, 22 Nov 2011 13:42:09 -0800
From:      Doug Barton <dougb@FreeBSD.org>
To:        Eitan Adler <eadler@freebsd.org>, src-committers@freebsd.org,  svn-src-all@freebsd.org, svn-src-head@freebsd.org, bde@freebsd.org,  theraven@freebsd.org, dim@freebsd.org, Brooks Davis <brooks@freebsd.org>
Subject:   Re: svn commit: r227812 - head/lib/libc/string
Message-ID:  <4ECC1731.8010509@FreeBSD.org>
In-Reply-To: <20111122202735.GA21442@zim.MIT.EDU>
References:  <201111220250.pAM2oPWC070856@svn.freebsd.org> <20111122153332.GA20145@zim.MIT.EDU> <CAF6rxgmPeZCZ3c0xbd-4riqvLHob8U9eWG25R8P6FG2BjTfyyA@mail.gmail.com> <20111122202735.GA21442@zim.MIT.EDU>

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On 11/22/2011 12:27 PM, David Schultz wrote:
> On Tue, Nov 22, 2011, Eitan Adler wrote:
>> The problem with profiling this type of change is that it is hard to
>> find a good representative benchmark. I could easily write code that
>> will show you that adding the equality check is a good idea or that it
>> is a horrible idea. IMHO it saves enough time when they are equal, but
>> loses almost no time when the strings are not equal.
> 
> Benchmark or not, I think you'll have a very hard time finding a
> single real program that routinely calls strcasecmp() with
> identical pointers!

Agreed. Also, these changes seem to violate the general rule of "Don't
call a change an optimization unless you have benchmarks that
demonstrate that it actually is." The more critical the piece of code
you are modifying, the more important this rule is.

>> Is this the right course of action? Or should I just revert both
>> commits entirely?

Sorry to say, my vote would be to back them out. OTOH, I agree with
David that you should try not to let it discourage you.


Doug

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