Re: octave dev slow down

[Mike Miller]

On Tue, May 23, 2017 at 12:16:07 -0400, John W. Eaton wrote:
> On 05/23/2017 04:37 AM, Mike Miller wrote:
> 
> > Confirmed here. I bisected and found a lot of performance loss starting
> > with c452180ab672. Its immediate predecessor f4d4d83f15c5 has about the
> > same performance as 4.2.1. If you can compare those two revisions and
> > confirm, that's a good place to start looking for a cause.
> 
> What was your test for performance here?
> 
> I recall timing "make check" when I made those changes and did not see a
> significant change in performance.
> 
> If I have something to test, I'll take a look at it.

I ran Dmitri's test case a handful of times at each build revision. I
get a distinct difference between f4d4d83f15c5 and c452180ab672, all
other things being equal. I'm using OpenBLAS instead of ATLAS.

I ran multiple Octave sessions with -cli -W, built without Qt to speed
up bisecting, using the test case "x = rand(4000); tic; x'*x; toc".

f4d4d83f15c5: mean is 0.63071 seconds, std dev is 0.0024187.

c452180ab672: mean is 1.1713 seconds, std dev is 0.11803.

This is the test case that I used to bisect and the results stayed
consistent and converged on this revision.

-- 
mike