Catégories: "Informatique"

Status of LLVM in Debian

Mai 17th, 2011

Here is some updates on the LLVM world into Debian.
LLVM and CLANG getting better and better after each release. After some lag, it is now time to have all these packages up-to-date into the archive.

Here is an update of their status in Debian:

  • LLVM
    LLVM 2.8 and 2.9 are now available into the archive.
    For version 2.8, Matthias Klose deserves most of the credit.
    Version 2.9 is available in experimental.

    They both build pretty well on most of the architectures besides kfreebsd. It is on my TODO list.

  • Clang. A C/C++ compiler.
    clang 2.8 and 2.9 are respectively available in unstable and experimental.
    These versions cover most of C/C++ specifications and more and more big software (Qt, Boost, Scilab, etc) succeed to be built with it.

    Like LLVM, it is available under most of the Debian architectures (but I haven't tested the quality of the ASM generated).

    clang can be used just like gcc. With most of software, calling configure/make with CC="clang" or CXX="clang" should be enought.

  • * Dragonegg
    Dragonegg is a gcc plugin (llvm-gcc-4.5) which allows gcc to use optimizer and code generators of LLVM.
    It is now straightforward to use:

    llvm-gcc -o foo foo.c

    I have lighten the "contact" between the gcc version used to build the extension and the version used to run it.
    It required the exact same version of gcc (even if the sources say it is probably a too strong requirement).

    Now, a warning like this one is displayed:

    Potential incompatible plugin version. GCC: 4.5.3. Expected: 4.5.2
    Defines 'dragonegg_disable_version_check' as env variable to remove this warning
    Please note that unexpected errors might occur.

    If there is a better way to tackle this issue, I will be happy to hear it.

  • llvm-defaults
    Last but not least, I uploaded llvm-defaults, a work of Arthur Loiret. This package allows a similar behavior to gcc-defaults. The installation of llvm will provide the default version of llvm.

Deprecated stuffs:

  • llvm
    The llvm package has been removed. Actually, it was just the version 2.6 of llvm (see bug #625729). llvm (from llvm-defaults) is now providing the favorite version of llvm.

  • llvm-gcc-4.2
    Upstream stopped the development of this plugin.
    It has been removed from the archive (see bug #626007) and dragonegg is taking the relay.

  • llvm-snapshot
    llvm-snapshot (see bug #626083) followed the same direction as llvm-gcc-4.2

  • llvm-2.7
    llvm-2.7 is still in the archive (see bug #626081) because of some reverse dependencies...

Google Summer of code at Scilab

Avril 29th, 2010

First, a quick news. Scilab 5.2.2 has been released a few days and he now available in the Debian archive (Debian Unstable for now).
It is mostly a performance improvements and bug fixes release. See the changelog.

Second, for a second year, Scilab is part of the Google Summer of Code v2010. I am admin (and also mentor) this year again.
Google just released the list of accepted students. We have 9 students (against 7 last year). 2 are working on experimental projects, the other should have a finished result by the end of the GSoC.

Extends Scilab UI Control - Han Dong
Extension of Scilab User Interface construction (uicontrol) by providing more elements (tree, image display, etc).

Simulink import in Xcos - Jerzy Zagorski
Importation of most of the Simulink schemas from Xcos.

Cumulative distribution function improvements - Michael Zhang
Improvement and extension of the current cumulative distribution functions (CFD) into Scilab.

Metanet and Boost.graph - Balša Raičević
Extension of the Metanet capabilities in term of graphs by Boost.graph

SOAP Client/server - Artem Glebov
Making available from Scilab both SOAP client and server capabilities as an ATOMS module.

Database module + fuzzySQL - Igor Gridchyn
Allow to access to most databases systems from Scilab. Based on this work, the FuzzySQL will be introduced, a SQL extension to allow flexible conditions in queries.

Python import - Baozeng Ding
Introduction of a mechanism to load and use Python code (objects in particular) from Scilab.

Experimental projects:
Use Eigen into Scilab - Joseph Fahnbulleh
Base some components of the Scilab core code on the Eigen library which is a state-of-the-art C++ linear algebra library. This work will be a joint mentoring between Gaël Guennebaud from the Eigen team and Scilab R & D team.

Hybrid Automata module - Ievgen Ivanov
Provide a convenient environment for direct modeling of hybrid automata in Scilab/Xcos.

Update of the linear algebra libraries in Debian

April 6th, 2010

In the numerical computing world, the cornerstones libraries are BLAS and LAPACK. They have been used in most of the numerical software for decades (like Scilab, R, numpy, OpenOffice with calc, etc).

During that time, many implementations appeared to improve the performances taking advantages of clusters, multicore, SEE{1,2,3,4}, various levels of cache...
Between the reference BLAS (refblas) to an optimized one like ATLAS or MKL (Math Kernel Library by Intel - non-free), it is not rare to have a 15 factor.

In Debian, we use by default the reference implementation of BLAS (168 reverse dependencies) and LAPACK (178 reverse dependencies). If the results are usually bad, they are pretty easy to use. What is hard to use, is switch between highly optimized libraries.
For now, the main one in the archive is ATLAS. ATLAS build process will launch many computations to know what will work best on the architecture. Results are usually excellent.

1) Upload of a refactoring of the ATLAS package.
I have been working on this for a while and after 19 uploads into Debian Experimental and I am happy (and kind of relief) to upload into debian unstable the release 3.8.3 of ATLAS.

The new key elements in this release are:

  • Package of the release 3.8.3 ... Long overdue
  • Much more packages for recent architectures (sse3, core2sse3, etc)
  • A simplified maintenance
  • Easy to build a custom package: fakeroot debian/rules custom
  • Easy upgrade to version 3.9.X when it is stable
  • 12 bugs closed in Debian (including 4 RCs)
  • 6 bugs closed in Launchpad.
  • MMX optimized package removed

Note that, as before, all prebuilt binaries of ATLAS will be always slower than if you built them on the target architecture (but using Debian binary packages will save a few kilograms of Uranium).

And one of most important feature is the capability to switch to any ATLAS implementation.

2) Switch between the different implementation
The problem in Debian (and Ubuntu) was that it was hard to switch between the ref BLAS/LAPACK and the optimized libraries. The user has to play with the LD_LIBRARY_PATH to use the various optimized packages and since there is no convention between the various distribution, the upstream developer has to develop crappy tricks to handle such things.

It is why I implemented the following proposal: Handle different versions of BLAS and LAPACK.

The main idea is to use the update-alternatives system to allow a quick and easy switch. For example:

# update-alternatives --config libblas.so.3gf 
There are 3 choices for the alternative libblas.so.3gf (providing /usr/lib/libblas.so.3gf).

  Selection    Path                                           Priority   Status
------------------------------------------------------------
* 0            /usr/lib/atlas-core2sse3/atlas/libblas.so.3gf   55        auto mode
  1            /usr/lib/atlas-base/atlas/libblas.so.3gf        35        manual mode
  2            /usr/lib/atlas-core2sse3/atlas/libblas.so.3gf   55        manual mode
  3            /usr/lib/libblas/libblas.so.3gf                 10        manual mode

# update-alternatives --config liblapack.so.3gf
There are 3 choices for the alternative liblapack.so.3gf (providing /usr/lib/liblapack.so.3gf).

  Selection    Path                                             Priority   Status
------------------------------------------------------------
* 0            /usr/lib/atlas-core2sse3/atlas/liblapack.so.3gf   55        auto mode
  1            /usr/lib/atlas-base/atlas/liblapack.so.3gf        35        manual mode
  2            /usr/lib/atlas-core2sse3/atlas/liblapack.so.3gf   55        manual mode
  3            /usr/lib/lapack/liblapack.so.3gf                  10        manual mode

Thanks to this, it is just trivial to switch from one to the other...

Conclusion:
I just pushed the changes into Debian unstable for blas, lapack and atlas.
I have been testing a lot these deep modifications and I fixed all the problems that I found. However, in case I missed something, please report a bug...

Back from the dead

April 6th, 2010

I know, my blog is pretty much dead. Not much time to blog on my various travels.
However, I am going to try to resurrect it for Debian and Scilab.

My next messages related to Debian will be also published on Debian Planet.

A few news around Scilab (packaging & other stuff)

Décembre 30th, 2008

Here is a quick list of new things around Scilab (note that it is slightly modified message of the one I sent on the dev mailing list).

  • Sagemath - it is a software which combines the power of various opensource software.

    A Experimental "Scilab/Sage package" is planed for Sage 3.4 and an experimental package by Jaap Spies is already available

  • Debian/Ubuntu
    Packages are available on my Scilab homepage
    Debian packages are up-to-date (5.0.3-2). I will to upload the new Ubuntu's packages in 2009 (for now, it is 5.0.3-1 which is working too). I might backport them to Debian Lenny (future stable) & Ubuntu Hardy.

  • Mandriva
    Tomasz Pawel Gajc (a regular Mandriva contributor) created a package available on zarb.org

  • Opensuse
    A Scilab package for Opensuse has been created by Andrea Florio.
    It is available on packman
    and should be included in the next version of opensuse.
    Note that Mandriva & Opensuse packages have been created for Scilab 5.0.3 and I applied most of their patches (or update some part of the code) for Scilab 5.0.4.

  • Redhat/Fedora
    The work is still going on.
    They are also doing a great work packaging the misc dependencies but they are a bit stuck about the JOGL packaging (jogl and glugen should produce two different packages ... which I should also do in Debian/Ubuntu too)

  • Arch Linux
    It is also available under Arch Linux by Simon Lipp (one of our former trainee).

  • Gentoo
    A bit stuck for now but some activities have been seen lately around on jrosetta (one of the dependency introduced by Scilab 5).

  • Slackware
    Scilab has been packaged by the Italian Slackware community. It is available on their website. I don't know if it is going to be included in Slackware by default or not;