[Pandas-dev] #3089 [PERF: regression from 0.10.1] discussion

[Jeff Reback]

It was an academic exercise :)

not that these are actual quotes....

"premature optimization is the root of all evil"

"benchmarking to widgets just helps you make better widgets"

On Mar 20, 2013, at 1:25 AM, Stephen Lin <swlin at post.harvard.edu> wrote:

> Ahh! I figured it out...the platform issue is part of it, but mostly
> it's that two (independently tested) commits had a weird effect when
> merged.
> 
> And the reason they did so is because this particular test turns out
> all of our reindexing tests are testing something very
> non-representative, because of the way they're constructed, so we're
> not really getting representative performance data unfortunately (it
> has to do with the DataFrame constructor and c-contiguity vs
> f-contiguity). We should probably write new tests to fix this issue.
> 
> I'll write up a fuller explanation when I get a chance. Anyway, sorry
> for sending you on a git bisect goose chase, Jeff.
> 
> Stephen
> 
> On Wed, Mar 20, 2013 at 1:01 AM, Stephen Lin <swlin at post.harvard.edu> wrote:
>> As per the "we're getting too chatty on GitHub" comment, should we be
>> moving extended issue discussion about bugs to this list whenever
>> possible?
>> 
>> I posted a few comments on #3089 just now but realized maybe starting
>> an e-mail chain would be better..
>> 
>> Anyway, I'm looking into the issue, I suspect it's a corner case due
>> to an array that's very large in one dimension but small in another,
>> and possibly that there's compiler and architecture differences
>> causing different results as well....Jeff, do you mind sending me your
>> the output of "gcc -dumpmachine" and "gcc -dumpspecs" on the machine
>> you ran vb_suite on?
>> 
>> I'll set up a 64-bit dev machine going forward so I can test on both platforms.
>> 
>> Thanks,
>> Stephen
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