Re: [eigen] Small dynamic matrix optimization |

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*To*: eigen@xxxxxxxxxxxxxxxxxxx*Subject*: Re: [eigen] Small dynamic matrix optimization*From*: Darcy Beurle <darcy.beurle@xxxxxxxxxxxxxxxxxxxx>*Date*: Mon, 21 Oct 2019 18:12:02 +0200

Is there anyway to access the alignment through a type trait of the matrix class? Passing the correct alignment of the underlying storage to the Eigen::Map would then be a simple task, albeit ugly. Cheers, Darcy On Mon, 2019-10-21 at 16:35 +0200, Christoph Hertzberg wrote: > If you can ensure that the allocated memory is aligned, you can use > `Map<Matrix<...>, Aligned>`. Also, we do allow vectorization of > non-aligned data (with newer CPUs there is barely a performance > difference, except when loads/store are split between cache-lines). > > Btw: There is a macro `ei_declare_aligned_stack_constructed_variable` > in > Eigen/src/Core/util/Memory.h which already does most of what you need > to > do (grep the source code to see where/how it is used). > > Cheers, > Christoph > > > On 21/10/2019 16.21, Rob Conde wrote: > > Thanks...I will think about this and maybe try to prototype > > something. > > > > Using the Map approach...I think this would disable SIMD right? > > Because you don't know if the mapped data is aligned? > > > > Rob > > ________________________________ > > From: Christoph Hertzberg <chtz@xxxxxxxxxxxxxxxxxxxxxxxx> > > Sent: Monday, October 21, 2019 10:15 AM > > To: eigen@xxxxxxxxxxxxxxxxxxx <eigen@xxxxxxxxxxxxxxxxxxx> > > Subject: Re: [eigen] Small dynamic matrix optimization > > > > This is already done for some temporaries (like blocks in > > cache-optimized GEMM). Doing that for custom types would be > > interesting, > > but not trivial (e.g., move-behavior is completely different, if > > you > > want to move the data to an object higher in the stack). > > > > If you are ok with managing data yourself, you can manually achieve > > this > > by alloca/allocate-ing data yourself and use an Eigen::Map to refer > > to > > the data. > > > > If you have a proof-of-concept how this could be integrated into > > the > > Eigen API, we are open for suggestions! > > > > Another idea would be to allow custom allocators for matrices -- in > > that > > case the custom allocator could very easily be a stack-allocator > > (which > > would not even need to use the "main" stack). But that's also not > > too > > easy to integrate without breaking the current API (adding a new > > type > > would of course be an option for that). > > > > Cheers, > > Christoph > > > > > > > > On 21/10/2019 15.39, Rob Conde wrote: > > > I'm wondering if a small dynamic matrix optimization has been > > > considered. In other words, allowing a stack allocation for > > > matrices of unknown size up to a certain limit and using a heap > > > allocation beyond that? > > > > > > Rob Conde > > > > > > > -- > > Dr.-Ing. Christoph Hertzberg > > > > Besuchsadresse der Nebengeschäftsstelle: > > DFKI GmbH > > Robotics Innovation Center > > Robert-Hooke-Straße 5 > > 28359 Bremen, Germany > > > > Postadresse der Hauptgeschäftsstelle Standort Bremen: > > DFKI GmbH > > Robotics Innovation Center > > Robert-Hooke-Straße 1 > > 28359 Bremen, Germany > > > > Tel.: +49 421 178 45-4021 > > Zentrale: +49 421 178 45-0 > > E-Mail: christoph.hertzberg@xxxxxxx > > > > Weitere Informationen: http://www.dfki.de/robotik > > ------------------------------------------------------------- > > Deutsches Forschungszentrum für Künstliche Intelligenz GmbH > > Trippstadter Strasse 122, D-67663 Kaiserslautern, Germany > > > > Geschäftsführung: > > Prof. Dr. Jana Koehler (Vorsitzende) > > Dr. Walter Olthoff > > > > Vorsitzender des Aufsichtsrats: > > Prof. Dr. h.c. Hans A. Aukes > > Amtsgericht Kaiserslautern, HRB 2313 > > ------------------------------------------------------------- > > > > > > > >

**References**:**[eigen] Should we require c++11 for Eigen tensor***From:*Rasmus Munk Larsen

**Re: [eigen] Should we require c++11 for Eigen tensor***From:*Christoph Hertzberg

**Re: [eigen] Should we require c++11 for Eigen tensor***From:*William Tambellini

**Re: [eigen] Should we require c++11 for Eigen tensor***From:*Rasmus Munk Larsen

**[eigen] Small dynamic matrix optimization***From:*Rob Conde

**Re: [eigen] Small dynamic matrix optimization***From:*Christoph Hertzberg

**Re: [eigen] Small dynamic matrix optimization***From:*Rob Conde

**Re: [eigen] Small dynamic matrix optimization***From:*Christoph Hertzberg

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