Your message dated Sat, 05 Aug 2023 22:04:30 +0000
with message-id <[email protected]>
and subject line Bug#1025480: fixed in openblas 0.3.13+ds-3+deb11u1
has caused the Debian Bug report #1025480,
regarding libopenblas0-pthread: gives wrong results with AVX-512 kernel
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
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-- 
1025480: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1025480
Debian Bug Tracking System
Contact [email protected] with problems
--- Begin Message ---
Package: libopenblas0-pthread
Version: 0.3.13+ds-3
Severity: important
Tags: upstream
X-Debbugs-Cc: [email protected]

Dear Maintainer,

While upgrading my debian OS from 10.x to 11.x (octave 4.4.5 to 6.2.0),
one of my scripts started failing. I managed to create the following test
that reproduces the problem:
--------
% non-singular matrix
b=[7110.327, -2592.219, 631.419, -288.541, 169.250, -113.431, 82.646, -63.812, 
51.448, -42.914;
 -1218.551, 1508.124, -720.486, 169.250, -74.433, 42.572, -28.131, 20.364, 
-15.701, 12.683;
 169.250, -482.641, 674.499, -350.244, 82.646, -36.010, 20.364, -13.333, 9.592, 
-7.371;
 -49.544, 82.646, -268.958, 399.001, -215.550, 51.448, -22.463, 12.683, -8.285, 
5.950;
 20.364, -27.810, 51.448, -178.696, 275.664, -152.325, 36.804, -16.173, 9.164, 
-6.000;
 -10.260, 12.683, -18.791, 36.804, -132.946, 211.205, -118.438, 28.958, 
-12.831, 7.317;
 5.950, -6.944, 9.164, -14.257, 28.958, -107.451, 174.780, -99.104, 24.511, 
-10.963;
 -3.839, 4.320, -5.318, 7.317, -11.762, 24.511, -92.803, 153.928, -88.144, 
22.050;
 2.702, -2.966, 3.488, -4.451, 6.304, -10.377, 22.050, -84.854, 143.052, 
-82.752;
 -2.050, 2.211, -2.519, 3.056, -4.000, 5.789, -9.704, 20.944, -81.727, 139.664];
sizeb=n=size(b,1)
rankb=rank(b)
% Builds blocked matrix
B=[eye(n) zeros(n); zeros(n) b];
% Computes inverse
inv1=inv(B);
% Computes inverse by blocks: non-trivial block:
invb=inv(b);
% Build inverse by blocks
inv2=[eye(n) zeros(n); zeros(n) invb];
% Both inverse matrices should be equal
diffinvs=norm(inv1-inv2)
% All these condition numbers should be 1
cond(inv1*B)
cond(B*inv1)
cond(inv2*B)
cond(B*inv2)
--------
The computation of "inv1" gives wrong results in:
-Intel Core i9-9900X
-Intel Core i9-7900X
-Intel Core i5-1035G1
and correct results in:
-Intel Core i5-750
-Intel Core i7-4930K
What pointed me in the direction of a trheads problem was the fact that
setting OMP_NUM_THREADS to 1 modify the output of the computation, (given
correct results in some cases).
The last tests I performed were running octave preloading the pthreads
and the openmp openblas libraries:
LD_PRELOAD=/usr/lib/x86_64-linux-gnu/openblas-pthread/libopenblas.so.0 
octave-cli test.m
gives incorrect results, while
LD_PRELOAD=/usr/lib/x86_64-linux-gnu/openblas-openmp/libopenblas.so.0 
octave-cli test.m
works ok.

(by "works ok" I mean the inverse computed by both methods differ only in the
floating point precision:~2e-17 and all the condition numbers are 1, In the
case of "failure", the inverses differ by ~0.035 and the condition numbers of
inv1*B and B*inv1 are about 4.7-4.9)


-- System Information:
Debian Release: 11.5
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 5.10.0-18-amd64 (SMP w/20 CPU threads)
Kernel taint flags: TAINT_FIRMWARE_WORKAROUND
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), 
LANGUAGE=en_US:en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages libopenblas0-pthread depends on:
ii  libc6         2.31-13+deb11u5
ii  libgfortran5  10.2.1-6

libopenblas0-pthread recommends no packages.

libopenblas0-pthread suggests no packages.

-- no debconf information

--- End Message ---
--- Begin Message ---
Source: openblas
Source-Version: 0.3.13+ds-3+deb11u1
Done: Sébastien Villemot <[email protected]>

We believe that the bug you reported is fixed in the latest version of
openblas, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to [email protected],
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Sébastien Villemot <[email protected]> (supplier of updated openblas package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing [email protected])


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

Format: 1.8
Date: Sun, 25 Jun 2023 21:56:08 +0200
Source: openblas
Architecture: source
Version: 0.3.13+ds-3+deb11u1
Distribution: bullseye
Urgency: medium
Maintainer: Debian Science Team 
<[email protected]>
Changed-By: Sébastien Villemot <[email protected]>
Closes: 1025480
Changes:
 openblas (0.3.13+ds-3+deb11u1) bullseye; urgency=medium
 .
   * avx512-dgemm.patch: new patch taken from upstream. Fixes incorrect 
numerical
     results of DGEMM on AVX512-capable hardware, when the package has been 
built
     on pre-AVX2 hardware (e.g. Intel Ivybridge). (Closes: #1025480)
Checksums-Sha1:
 3486863ff158510f282fce9d09a04b95f08b0a41 5075 openblas_0.3.13+ds-3+deb11u1.dsc
 74a7dffd9c6ac7f1ad1e01703581ee98f87e570b 24772 
openblas_0.3.13+ds-3+deb11u1.debian.tar.xz
 a81665a0e5b17dcbfd4a7ca181eabb816340f44e 14885 
openblas_0.3.13+ds-3+deb11u1_amd64.buildinfo
Checksums-Sha256:
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openblas_0.3.13+ds-3+deb11u1.dsc
 a53da98486d5040ac89564fc2c07de336c455a6dbc34d7550c6d448ceb3edbd0 24772 
openblas_0.3.13+ds-3+deb11u1.debian.tar.xz
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openblas_0.3.13+ds-3+deb11u1_amd64.buildinfo
Files:
 7698e2361c891bdee030677562ab6195 5075 devel optional 
openblas_0.3.13+ds-3+deb11u1.dsc
 7a513706f0a1a287c248cb72a944a58f 24772 devel optional 
openblas_0.3.13+ds-3+deb11u1.debian.tar.xz
 64678d7be01aeb6a148399a5c1d56117 14885 devel optional 
openblas_0.3.13+ds-3+deb11u1_amd64.buildinfo

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--- End Message ---
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