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[Octave-bug-tracker] [bug #55564] GESDD: vastly different singular value
From: |
Dmitri A. Sergatskov |
Subject: |
[Octave-bug-tracker] [bug #55564] GESDD: vastly different singular values when vectors are also requested |
Date: |
Thu, 24 Jan 2019 21:20:24 -0500 (EST) |
User-agent: |
Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:64.0) Gecko/20100101 Firefox/64.0 |
Follow-up Comment #7, bug #55564 (project octave):
May be we should revisit bug 49940.
It looks to me that gesvd mostly runs single-thread
even with multithreaded blas.
I run a simple benchmark and watched top. With
gesdd cpuload was 400% (4 threads), with
gesvd it started ~400% but dropped quickly to 100%
LD_PRELOAD=/usr/lib64/libopenblaso.so OMP_NUM_THREADS=4 ./run-octave
octave:1> a=randn(3000);
octave:2> tic; [u2,s2,v2] = svd (a); toc
Elapsed time is 13.4637 seconds.
octave:3> svd_driver("gesvd")
octave:4> tic; [u2,s2,v2] = svd (a); toc
Elapsed time is 247.86 seconds.
similar results with liopenblasp (pthread interface) and atlas.
I am not sure if this is octave problem (posted results in 49940
did not show such a big difference), or lapack's.
Dmitri.
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- [Octave-bug-tracker] [bug #55564] GESDD: vastly different singular values when vectors are also requested, anonymous, 2019/01/24
- [Octave-bug-tracker] [bug #55564] GESDD: vastly different singular values when vectors are also requested, Rik, 2019/01/24
- [Octave-bug-tracker] [bug #55564] GESDD: vastly different singular values when vectors are also requested, Mike Miller, 2019/01/24
- [Octave-bug-tracker] [bug #55564] GESDD: vastly different singular values when vectors are also requested, Mike Miller, 2019/01/24
- [Octave-bug-tracker] [bug #55564] GESDD: vastly different singular values when vectors are also requested, Rik, 2019/01/24
- [Octave-bug-tracker] [bug #55564] GESDD: vastly different singular values when vectors are also requested, Rik, 2019/01/24
- [Octave-bug-tracker] [bug #55564] GESDD: vastly different singular values when vectors are also requested, Mike Miller, 2019/01/24
- [Octave-bug-tracker] [bug #55564] GESDD: vastly different singular values when vectors are also requested,
Dmitri A. Sergatskov <=
- [Octave-bug-tracker] [bug #55564] GESDD: vastly different singular values when vectors are also requested, Rik, 2019/01/25
- [Octave-bug-tracker] [bug #55564] GESDD: vastly different singular values when vectors are also requested, Dmitri A. Sergatskov, 2019/01/25
- [Octave-bug-tracker] [bug #55564] GESDD: vastly different singular values when vectors are also requested, Mike Miller, 2019/01/25
- [Octave-bug-tracker] [bug #55564] GESDD: vastly different singular values when vectors are also requested, Rik, 2019/01/25
- [Octave-bug-tracker] [bug #55564] GESDD: vastly different singular values when vectors are also requested, Tim Mitchell, 2019/01/25
- [Octave-bug-tracker] [bug #55564] GESDD: vastly different singular values when vectors are also requested, Rik, 2019/01/25
- [Octave-bug-tracker] [bug #55564] GESDD: vastly different singular values when vectors are also requested, Rik, 2019/01/25