[Dachs-support] DaCHS dachs command returns illegal instruction

Stéphane Erard stephane.erard at obspm.fr
Fri Nov 10 09:24:30 CET 2023


Dear all

I think there is still something to fix in the registry. When I look for idoc in TOPCAT, it sends me to 
http://idoc-dachs.ias.u-psud.fr/tap
But a request there gives:
	The document has moved <a href="https://idoc-dachs.ias.u-psud.fr/tap/sync">here</a>

Then, the https URL works fine (including in the VESPA portal where all IAS services where down for some time) - it seems that you want to remove the /sync part, though

Cheers
Stéphane




> Le 9 nov. 2023 à 16:11, Nima Traore <nima.traore at universite-paris-saclay.fr> a écrit :
> 
> Hi Markus,
> 
> Thank you very much for these suggestions :) Our server is up and running again.
> 
> We just changed the CPU type for the virtual machine (from kvm64 -> SandyBridge), then a stop/start to apply the change, and dachs works correctly again.
> 
> ~$ dachs --version
> Software (2.8.2) Schema (34/34)
> 
> Thank you very much again for your help.
> 
> Best regards,
> 
> Nima
> 
> De: dachs-support-request at g-vo.org
> À: "dachs-support" <dachs-support at g-vo.org>
> Envoyé: Mercredi 8 Novembre 2023 12:00:01
> Objet: Dachs-support Digest, Vol 32, Issue 4
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>    1. Re: DaCHS dachs command returns illegal instruction
>       (Markus Demleitner)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Tue, 7 Nov 2023 09:26:05 -0700
> From: Markus Demleitner <msdemlei at ari.uni-heidelberg.de>
> To: dachs-support at g-vo.org
> Subject: Re: [Dachs-support] DaCHS dachs command returns illegal
>         instruction
> Message-ID: <20231107162605.fzwm4nt3tihnk2cg at victor>
> Content-Type: text/plain; charset=utf-8
> 
> Hi Nima,
> 
> On Tue, Nov 07, 2023 at 12:37:43PM +0100, Nima Traore wrote:
> > Thank you very much for this information :) Here is below the
> > output of the where command in the gdb:
> >
> > ~$ gdb `which python3` core
> [...]
> > Core was generated by `/usr/bin/python3 /usr/bin/dachs --version'.
> > Program terminated with signal SIGILL, Illegal instruction.
> > #0 0x00007fb95b366820 in dgemm_otcopy_OPTERON_SSE3 () from /lib/x86_64-linux-gnu/libopenblas.so.0
> 
> Ha!  It helps!  You see, what this tells you is that the crash is in
> the blas library, which is venerable numberics code.  You probably
> didn't install this yourself; I think it was pulled in as  a
> dependency of numpy.
> 
> The name of the function the crash happens in is another hint:
> OPTERON_SSE3 suggests that this is code compiled for some AMD
> architecture -- and that the processor that actually executes the
> code doesn't understand some particular Opteron SSE3 opcode.
> 
> Of course, the real question is: How to fix that?
> 
> Well:
> 
>   $ apt info libopenblas0
>   [...]
>   Description: Optimized BLAS (linear algebra) library (meta)
>    OpenBLAS is an optimized BLAS library based on GotoBLAS2 1.13 BSD version.
>    .
>    On amd64, arm64, i386, ppc64el, s390x, kfreebsd-amd64 and kfreebsd-i386,
>    all kernels are included in the library and the one matching best your
>    processor is selected at runtime.
>    [...]
> 
> Hu!  If this were true, what you're seeing shouldn't be happening;
> your Opteron SSE3 function should only be attempted if you're
> actually *running* on a CPU that can execute it.  At this point, I
> admitted defeat as far as rational problem analysis.
> 
> In other words: I fed
> 
>   dgemm_otcopy_OPTERON_SSE3 "SIGILL"
> 
> to a web search engine.  It turns out you're not the first to
> experience this.  Here's a bug against openblas that analyses the
> problem in some detail:
> https://github.com/OpenMathLib/OpenBLAS/issues/2794
> 
> I've only skimmed that report (I'm supposed to listen to a conference
> talk now:-); perhaps you can study it a bit closer, but it would seem
> that solutions would involve recompiling, which I'd rather avoid.
> But then there's /usr/share/doc/libopenblas0/README.Debian, which
> explains how to switch blas implementations.  Can you have a look at
> it and the
> http://wiki.debian.org/DebianScience/LinearAlgebraLibraries that's
> linked for there?
> 
> If any of that fixes, your problem, would you let us know?  If not or
> you get stuck, feel free to ask back.  Or use a different
> virtualisation software (which I think is the root cause of your
> problem), or move to Intel- or ARM-based hardware (assuming things
> aren't even more broken that it seems and you already are on one), or
> use don't use a virtualised host at all and use actual hardware.
> 
> Sorry I can't be more specific...
> 
>           -- Markus
> 
> 
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