Enable multi-thread support for atlas in ubuntu packages for multicore architectures

Bug #604574 reported by Olivier Grisel on 2010-07-12
14
This bug affects 3 people
Affects Status Importance Assigned to Milestone
atlas (Ubuntu)
Undecided
Unassigned

Bug Description

It would be very appreciated if the atlas packages shipped in ubuntu by default could provide a variant to leverage multi-core architectures such as the core2 by enabling the multi-threading build option.

The upstream debian package seems to have a core2sse3 variant that might provide this (although I have no debian install at hand to check).

In the mean time ubuntu users that want to leverage multi cores for linear algebra are required to build atlas from source manually or install a non free alternative such as the MKL.

Description: Ubuntu 10.04 LTS
Release: 10.04

libatlas3gf-sse2:
  Installed: 3.6.0-24ubuntu1
  Candidate: 3.6.0-24ubuntu1
  Version table:
 *** 3.6.0-24ubuntu1 0
        500 http://fr.archive.ubuntu.com/ubuntu/ lucid/universe Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: libatlas3gf-sse2 3.6.0-24ubuntu1
ProcVersionSignature: Ubuntu 2.6.32-23.37-generic 2.6.32.15+drm33.5
Uname: Linux 2.6.32-23-generic i686
NonfreeKernelModules: wl nvidia
Architecture: i386
Date: Mon Jul 12 13:59:55 2010
ProcEnviron:
 PATH=(custom, user)
 LANG=en_US.utf8
 SHELL=/bin/zsh
SourcePackage: atlas

Olivier Grisel (olivier-grisel) wrote :
description: updated
Sylvestre Ledru (sylvestre) wrote :

This is the case since 3.8.3-27 in Debian.
Note that Atlas will use two threads since it is set up at build time.

The best way to have all cores used is to build yourself atlas on the machine .

Sergio Callegari (callegar) wrote :

Building atlas on a modern processor such an i7 takes ~1 day, because the current atlas shipped in debian/ubuntu is too old and does not provide architectural defaults for modern processors.

As a matter of fact, it is completely impossible to build atlas on recent intel processor, because the build scripts are not compatible with the p-state cpu driver.

Furthermore, atlas as shipped in debian/ubuntu is slow to run because it "is terribly out of date, and was released only because the
threading rewrite it taking too long. If possible, you should use a developer release after testing that it works for your particular
platform. In particular, developer releases are *much* faster for any x86 that uses AVX or later SIMD ISA, or any machine with ncores >= 8." This is from the release notes of the version in ubuntu.

See https://bugs.launchpad.net/ubuntu/+source/atlas/+bug/1347026
https://bugs.launchpad.net/ubuntu/+source/atlas/+bug/1370405

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