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Date:      Mon, 26 Dec 2011 16:24:12 -0800
From:      Doug Barton <dougb@FreeBSD.org>
To:        Steve Kargl <sgk@troutmask.apl.washington.edu>
Cc:        svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org, Marius Strobl <marius@alchemy.franken.de>
Subject:   Re: svn commit: r228857 - in head/usr.bin: . csup
Message-ID:  <4EF9102C.6010606@FreeBSD.org>
In-Reply-To: <20111227000915.GA80162@troutmask.apl.washington.edu>
References:  <201112241216.pBOCGd1H012696@svn.freebsd.org> <4EF645D2.8080407@FreeBSD.org> <20111226102820.GT90831@alchemy.franken.de> <4EF8DC5B.9070404@FreeBSD.org> <20111226225136.GA79882@troutmask.apl.washington.edu> <4EF902EB.5050009@FreeBSD.org> <20111227000915.GA80162@troutmask.apl.washington.edu>

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On 12/26/2011 16:09, Steve Kargl wrote:
> On Mon, Dec 26, 2011 at 03:27:39PM -0800, Doug Barton wrote:
>> On 12/26/2011 14:51, Steve Kargl wrote:
>>> On Mon, Dec 26, 2011 at 12:43:07PM -0800, Doug Barton wrote:
>>>> On 12/26/2011 02:28, Marius Strobl wrote:
>>>>> On Sat, Dec 24, 2011 at 01:36:18PM -0800, Doug Barton wrote:
>>>>>> On 12/24/2011 04:16, Marius Strobl wrote:
>>>>>>>   On FreeBSD just use the MD5 implementation of libmd rather than that of
>>>>>>>   libcrypto so we don't need to relinquish csup when world is built without
>>>>>>>   OpenSSL.
>>>>>>
>>>>>> Did you benchmark this at all? I agree that keeping csup available
>>>>>> absent openssl is a good goal, but csup is a prototypical "tool that
>>>>>> does the same thing many thousands of times" so even tiny regressions
>>>>>> could add up to a large cost in wall clock time.
>>>>>
>>>>> Well, in a real world test updating the same base on an amd64 machine
>>>>> connected to the Internet
>>>>
>>>> Adding a network connection to the test is almost certainly going to
>>>> obscure the results beyond utility.
>>>
>>> Given that the majority of FreeBSD users will be pulling code
>>> from the internet, this seems to be the most relevant test.
>>
>> Sorry if I wasn't clear. The change was to how the md5 portion of csup
>> is linked. In order to isolate the effects of that change you have to
>> remove everything that isn't related to that change.
>>
>> But this is regression testing 101, so I'm sure that you know that already.
> 
> If 99% of the usage of csup goes over the internet and 95% of the
> execution time (as determined by a profiler) involves dealing with
> network,

Those are both completely theoretical of course.

> then worrying about libmd vs libcrypto is a waste of time.

This is really getting boring now. If a change makes performance worse
it shouldn't be made without a really good reason. There is absolutely
nothing controversial about that.

> Yes, I know you did not ask him to back out his change.  You asked
> him if he measured the impact on performance with that implication
> that he should run some performance test.  Marius ran additional
> tests (wasting his time) to answer your question.  Your response
> was essentially, "well, your really need to do the test this way
> (ie., no internet)", with the obvious implication of "please go
> do your test again."

If Marius was confused about what I was asking him to test, or he didn't
understand how to properly test his change, he should have asked. The
fact that he did some kind of test that didn't actually demonstrate
anything useful isn't my problem.

>> I understand that what you're really trying to do here is to take a shot
>> at me relative to my assertion that profiled libs should be off by
>> default. If you're going to respond in kind to every message I send it's
>> going to get boring really quick.
> 
> Nope. I'm concerned that your wasting valuable developer time. 

And I'm concerned about wasting the time of every FreeBSD user that uses
csup.

> If you 
> were really concerned with the performance, I suspect that you know
> how to do the tests you have asked of Marius. 

I'm not the one proposing to make the change, he is. It's up to HIM to
demonstrate that his change is moving us in the right direction.

> Now, let's read his commit message:
> 
>     On FreeBSD just use the MD5 implementation of libmd rather than
>     that of libcrypto so we don't need to relinquish csup when world
>     is built without OpenSSL.

I read his commit message, I understand what he's trying to accomplish.

> His change actually allows FreeBSD users to use csup if they are
> in a situation where WITHOUT_CRYPTO and/or WITHOUT_OPENSSL is
> required. 

Personally I've never seen anyone mention this as a problem.

> Yes, I know you want him to waste his time to come
> up with the perfect patch with Makefile magic to find libcrypto
> and fall back to libmd.  If you're really concerned about
> performance I'm fairly certain that Marius would be willing 
> to review your Makefile magic patch.

You're still missing the fundamental point that the person proposing the
change is the one who needs to demonstrate that the change is the right
way to go. Imagine that the scenario was reversed. You would no doubt be
demanding that I provide extensive evidence that my change was correct.


Doug

-- 

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