Re: [Valgrind-developers] Request For Comments: Verrou, a Valgrind tool for floating-point debugging

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Re: [Valgrind-developers] Request For Comments: Verrou, a Valgrind tool for floating-point debugging

Dallman, John-2

This is potentially interesting for what I do. Is the documentation at http://edf-hpc.github.io/verrou/vr-manual.html up to date?

 

Something that would be very useful would be control of the seed of the random number generator, so that we could repeat and debug cases that gave strange results.

 

The code I work on is a large mathematical modeller, with perhaps 70,000 functions. Rather than using an exclusion file, it would be very useful to have an inclusion file as an alternative, where one could specify only the functions that should be subject to perturbation. We'd like this because it’s quite difficult to adequately test various numerical algorithms outside the context of the modeller.

 

Best,

 

--

John Dallman

DF PL TO OT PC PDE

Technology & Innovation

Nullius in verba

 

Siemens Industry Sector

Siemens Industry Software Limited

Francis House, 112 Hills Road,

Cambridge CB2 1PH, United Kingdom

Tel.      :+44 (1223) 371554

Fax       :+44 (1223) 371700

[hidden email]

www.siemens.com/plm

 

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Registered number: 3476850.
Registered office: Faraday House, Sir William Siemens Square, Frimley, Surrey, GU16 8QD.


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Re: [Valgrind-developers] Request For Comments: Verrou, a Valgrind tool for floating-point debugging

Dallman, John-2

An additional request: it would be very useful to be able to turn perturbations on and off through Valgrind's client-request mechanism. The use case for this goes like this:

 

We have a number of internal algorithms that are used by many functional areas of our modeller. If we suspect that one of them is misbehaving under particular circumstances, it would be useful to turn on perturbations for only those circumstances.

 

·        An easy way to do this would be to use client requests on the code paths that lead there.  

·        An alternative would be to extend the inclusion file syntax to work like memcheck's exclusion syntax, where one can specify the call stack for memcheck errors that should be ignored.

 

Thanks,

 

--

John Dallman

DF PL TO OT PC PDE

Technology & Innovation

Nullius in verba

 

Siemens Industry Sector

Siemens Industry Software Limited

Francis House, 112 Hills Road,

Cambridge CB2 1PH, United Kingdom

Tel.      :+44 (1223) 371554

Fax       :+44 (1223) 371700

[hidden email]

www.siemens.com/plm

 

From: [ext] Dallman, John [mailto:[hidden email]]
Sent: Thursday, June 01, 2017 12:29 PM
To: 'Ivo Raisr' <[hidden email]>; 'FEVOTTE Francois' <[hidden email]>
Cc: '[hidden email]' <[hidden email]>; 'HULSEMANN Frank' <[hidden email]>; 'Valgrind Users' <[hidden email]>; 'LATHUILIERE Bruno' <[hidden email]>
Subject: Re: [Valgrind-users] [Valgrind-developers] Request For Comments: Verrou, a Valgrind tool for floating-point debugging

 

This is potentially interesting for what I do. Is the documentation at http://edf-hpc.github.io/verrou/vr-manual.html up to date?

 

Something that would be very useful would be control of the seed of the random number generator, so that we could repeat and debug cases that gave strange results.

 

The code I work on is a large mathematical modeller, with perhaps 70,000 functions. Rather than using an exclusion file, it would be very useful to have an inclusion file as an alternative, where one could specify only the functions that should be subject to perturbation. We'd like this because it’s quite difficult to adequately test various numerical algorithms outside the context of the modeller.

 

Best,

 

--

John Dallman

DF PL TO OT PC PDE

Technology & Innovation

Nullius in verba

 

Siemens Industry Sector

Siemens Industry Software Limited

Francis House, 112 Hills Road,

Cambridge CB2 1PH, United Kingdom

Tel.      :+44 (1223) 371554

Fax       :+44 (1223) 371700

[hidden email]

www.siemens.com/plm

 

-----------------
Siemens Industry Software Limited is a limited company registered in England and Wales.
Registered number: 3476850.
Registered office: Faraday House, Sir William Siemens Square, Frimley, Surrey, GU16 8QD.

-----------------
Siemens Industry Software Limited is a limited company registered in England and Wales.
Registered number: 3476850.
Registered office: Faraday House, Sir William Siemens Square, Frimley, Surrey, GU16 8QD.


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Re: [Valgrind-developers] Request For Comments: Verrou, a Valgrind tool for floating-point debugging

FEVOTTE Francois

Le jeudi 01 juin 2017 à 11:56 +0000, [hidden email] a écrit :
> An additional request: it would be very useful to be able to turn
> perturbations on and off through Valgrind's client-request mechanism.

This is already supported, and is documented here:
http://edf-hpc.github.io/verrou/vr-manual.html#vr-manual.feat.instr

> We have a number of internal algorithms that are used by many
> functional areas of our modeller. If we suspect that one of them is
> misbehaving under particular circumstances, it would be useful to turn
> on perturbations for only those circumstances.

That is a very good use case, which makes it worth using the
client-request mechanism (and thus recompiling the code) rather than an
exclusion list.

Thanks,
   François

--
François FÉVOTTE
Research Engineer
EDF – R&D – PERICLES
I23 (Analysis and Numerical Modeling)
7 boulevard Gaspard Monge
91120 Palaiseau - FRANCE

[hidden email]
Phone: +33 1 78 19 44 23




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Re: [Valgrind-developers] Request For Comments: Verrou, a Valgrind tool for floating-point debugging

Dallman, John-2
Francois wrote:
> John Dallman wrote:
> > ... control of the seed of the random number generator

> I actually think we had this feature in earlier versions of Verrou, and I'm
> not sure when and how it disappeared. But I opened an issue on Github
> (https://github.com/edf-hpc/verrou/issues/3) and will (re)introduce this
> feature as soon as I can.

Splendid, thanks very much.

> > ... very useful to have an inclusion file as an alternative ...

> This one is also in our todo list.

Thanks again!

> One way to avoid the problem is to let Verrou generate the whole list of
> functions it encounters during a test run, and then provide this list as
> an exclusion list.

With 70,000 functions, it's sadly easy to make mistakes doing it that way.

> > ... to turn perturbations on and off through Valgrind's client-request
> This is already supported, and is documented here:
> http://edf-hpc.github.io/verrou/vr-manual.html#vr-manual.feat.instr

Oh, excellent! Sorry I missed this. The inclusion/inclusion file approach
does have an advantage over client requests, in that it avoids other code
being included in the counts, and thus making it possible to see how source
changes affect the counts of floating-point instructions. This could be a
valuable tool for exploring optimisation.

> > misbehaving under particular circumstances, it would be useful to turn
> > on perturbations for only those circumstances.
> That is a very good use case, which makes it worth using the client-request
> mechanism (and thus recompiling the code) rather than an exclusion list.

Absolutely.

> Thank you for your interest in Verrou.

Thank you for writing it! This has lots of potential for us.

Best,

--
John Dallman

Siemens Industry Sector
Siemens Industry Software Limited
Francis House, 112 Hills Road,
Cambridge CB2 1PH, United Kingdom
Tel.      :+44 (1223) 371554
Fax       :+44 (1223) 371700
[hidden email]
www.siemens.com/plm


-----Original Message-----
From: FEVOTTE Francois [mailto:[hidden email]]
Sent: Friday, June 02, 2017 1:42 PM
To: Dallman, John (DF PL TO OT PC PDE) <[hidden email]>
Cc: [hidden email]
Subject: Re: [Valgrind-users] [Valgrind-developers] Request For Comments: Verrou, a Valgrind tool for floating-point debugging


Le jeudi 01 juin 2017 à 11:56 +0000, [hidden email] a écrit :
> An additional request: it would be very useful to be able to turn
> perturbations on and off through Valgrind's client-request mechanism.

This is already supported, and is documented here:
http://edf-hpc.github.io/verrou/vr-manual.html#vr-manual.feat.instr

> We have a number of internal algorithms that are used by many
> functional areas of our modeller. If we suspect that one of them is
> misbehaving under particular circumstances, it would be useful to turn
> on perturbations for only those circumstances.

That is a very good use case, which makes it worth using the client-request mechanism (and thus recompiling the code) rather than an exclusion list.

Thanks,
   François

--
François FÉVOTTE
Research Engineer
EDF – R&D – PERICLES
I23 (Analysis and Numerical Modeling)
7 boulevard Gaspard Monge
91120 Palaiseau - FRANCE

[hidden email]
Phone: +33 1 78 19 44 23




Ce message et toutes les pièces jointes (ci-après le 'Message') sont établis à l'intention exclusive des destinataires et les informations qui y figurent sont strictement confidentielles. Toute utilisation de ce Message non conforme à sa destination, toute diffusion ou toute publication totale ou partielle, est interdite sauf autorisation expresse.

Si vous n'êtes pas le destinataire de ce Message, il vous est interdit de le copier, de le faire suivre, de le divulguer ou d'en utiliser tout ou partie. Si vous avez reçu ce Message par erreur, merci de le supprimer de votre système, ainsi que toutes ses copies, et de n'en garder aucune trace sur quelque support que ce soit. Nous vous remercions également d'en avertir immédiatement l'expéditeur par retour du message.

Il est impossible de garantir que les communications par messagerie électronique arrivent en temps utile, sont sécurisées ou dénuées de toute erreur ou virus.
____________________________________________________

This message and any attachments (the 'Message') are intended solely for the addressees. The information contained in this Message is confidential. Any use of information contained in this Message not in accord with its purpose, any dissemination or disclosure, either whole or partial, is prohibited except formal approval.

If you are not the addressee, you may not copy, forward, disclose or use any part of it. If you have received this message in error, please delete it and all copies from your system and notify the sender immediately by return message.

E-mail communication cannot be guaranteed to be timely secure, error or virus-free.
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Registered number: 3476850.
Registered office: Faraday House, Sir William Siemens Square, Frimley, Surrey, GU16 8QD.
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