bugGNU Octave - Bugs: bug #54005, kron performance affected by...


bug #54005: kron performance affected by octave_quit() calls

Submitted by:  A.R. Burgers <arb>
Submitted on:  Tue 29 May 2018 08:34:32 PM UTC  
Category:  Interpreter Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Performance
Status:  None Assigned to:  None
Originator Name:  Open/Closed:  Open
Release:  4.4.0 Operating System:  Any

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Thu 31 May 2018 09:22:20 PM UTC, comment #3:

Well, the initial diff was only meant to highlight the issue.
Moving the octave_quit one level up, in case nrb==1 leads to these timings:

A.R. Burgers <arb>
Thu 31 May 2018 08:03:53 AM UTC, comment #2:

Of course, it is not Xgemm, but Xscal the proper BLAS routine for scaling a matrix.

Marco Caliari <caliari>
Project Member
Wed 30 May 2018 01:29:29 PM UTC, comment #1:

@A.R. Burgers: If you move octave_quit() outside, then you will never be able to interrupt the operation with a Ctrl+C, I think. Can you please measure what happens if you move octave_quit() to the other loops?

It seems to me that the operation here is made column by column on b. This is a general question: is scalar times a matrix a column by column operation in octave? Could not it be done by BLAS xgemm (with alpha=0)?

Marco Caliari <caliari>
Project Member
Tue 29 May 2018 08:34:32 PM UTC, original submission:

Kron execution times of 2 row vectors or 2 column vectors differ significantly:

The timings are

Moving the octave_quit() from the innermost loop to outside

makes the row vector case quite a bit faster:

A.R. Burgers <arb>


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