[LLVMdev] Why is the default LNT aggregation function min instead of mean

David Tweed david.tweed at gmail.com
Sat Jan 18 03:02:38 PST 2014

Note that it's very possible to get the those kind of effects from
other sources of computational load on the machine, see the fib35
graphs on


On Sat, Jan 18, 2014 at 12:57 AM, Tobias Grosser <tobias at grosser.es> wrote:
> On 01/17/2014 08:58 AM, Chris Matthews wrote:
>> Is it the case that you converge on the min faster than the mean?
> Sorry, I do not fully understand what you mean here. What exactly would I
> need to do to check this? Should I just pick a couple of test/run pairs and
> see after how many samples the min/mean does not change any more?
> What conclusion can I take from this?
>> Right now there is no way to set a per-tester aggregation function.
>> I had spent a little time trying to detect regressions using k-means
>> clustering.  It looked promising.  That was outside LNT though.
> Interesting idea and that would most likely be helpful in configurations
> where we actually get run-times clustered in different groups. I was
> initially assuming this, but after Chandlers comments I have the feeling we
> actually only have a single cluster where the statements are just grouped
> due to the limited resolution of the analysis.
> Cheers
> Tobias
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cheers, dave tweed__________________________
high-performance computing and machine vision expert: david.tweed at gmail.com
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