Re: [eigen] Decrease in performances

[Maxime REIS <maxime.reis@xxxxxxxxx>]

Hi,

Everything is fine up to the fix of 'Bug 363' :

- 4281:25ba289d5292 runs fast

- 4282:a07628375b86 doesn't compile

- 4283:f76f77b7d086 is sloooooooow

The bug fix apparently slowed down the whole thing, and the perfs were improved again in c29d777b278c (some 40 or so commits after the decrease), but not to the point they were before the bug fix.

I guess it's the price to pay to have a robust library. From that point on, all subsequent commits don't seem to affect overall performances (at least from my observations)

I don't know if it deserves further investigation....

Best regards,

Maxime REIS

On 25 June 2012 15:26, Gael Guennebaud <gael.guennebaud@xxxxxxxxx> wrote:

Hi,

in-between the 3.0.3 and 3.0.4 release I see only the 5 following
change-sets that could affect the performances:

248f1d7c5f86
dfea1f0cbf7a
e5f87fa9e5c2
f95322d996f2
9c5248ab7ac1

using bissection strategy you should be able to find exact change-set
that introduced a regression with at most 3 tries. Not that if you are
using SelfAdjointEigenSolver then the slowdown might simply be due to
to lack of precision in previous releases (see changeset
f95322d996f2).


thanks for your help,

gael

On Mon, Jun 25, 2012 at 12:10 PM, Maxime REIS <maxime.reis@xxxxxxxxx> wrote:
> Hi everyone,
>
> A few releases ago, I noticed a slight decrease in overall performances in
> my soft, using eigen. Since execution time is my main concern and the reason
> why I chose eigen in the first place, I ran a few tests to make sure :
> I recompiled my project using all 3.x releases of eigen (and some 2.0.x
> too), and compared the execution time of some algorithms I implemented..
> Versions 3.0.0 to 3.0.3 gave fairly stable results, but versions 3.0.4,
> 3.0.5 and 3.1 made my execution time up to 50% longer on some critical
> algorithms (performances are similar in the last three versions though). All
> my code uses mostly basic matrix operations (product, transpose, submatrix
> extraction) on fixed-size matrices.
>
> I can try and be more precise on what takes more time if needed, but I think
> the eigen benchmark suite would be better suited for that purpose (the last
> published bench is over a year old...)
> Has anyone else had similar problems with performances ?
>
> Regards,
> Maxime REIS.