[R-SIG-Mac] Change to BLAS (from default to Apple vecLib) doesn't report in sessionInfo()

[Kevin Ushey]

My suspicion is the code here:

https://github.com/wch/r-source/blob/068a6a0d9d60b1ce42abc879900038649f4a929c/src/main/platform.c#L3358-L3363

It seems that the call to 'realpath()' fails on the path reported via
.dli_fname here, which (for me) is:

/System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/vecLib.framework/Versions/A/libBLAS.dylib

And indeed, the library does not appear to exist at that location. I'm
not sure if this is a real macOS bug or some property of how vecLib /
macOS frameworks work, though.

For posterity, I'm on macOS Ventura 13.1, running on an M1 macOS machine.

> sessionInfo()
R version 4.2.1 (2022-06-23)
Platform: aarch64-apple-darwin20 (64-bit)
Running under: macOS Ventura 13.1

Matrix products: default
LAPACK: /Library/Frameworks/R.framework/Versions/4.2-arm64/Resources/lib/libRlapack.dylib

tl;dr: perhaps R should allow for failures in 'realpath()' above, at
least on macOS, and report the library path as gleaned directly from
dladdr()?

Thanks,
Kevin


On Tue, Jan 10, 2023 at 8:54 AM Clement Kent <clementfkent using gmail.com> wrote:
>
> I experienced the same thing. I switched to libRblas.vecLib.dylib and got
> the remarkable speedup
> in matrix multiplication, but sessionInfo doersn't show that I'm using it.
> MacBook Pro (14-inch, 2021)
>
> sessionInfo()
> R version 4.2.2 (2022-10-31)
> Platform: aarch64-apple-darwin20 (64-bit)
> Running under: macOS Monterey 12.6.2
>
> Matrix products: default
> LAPACK:
> /Library/Frameworks/R.framework/Versions/4.2-arm64/Resources/lib/libRlapack.dylib
>
> Random number generation:
>  RNG:     Mersenne-Twister
>  Normal:  Inversion
>  Sample:  Rounding
>
> locale:
> [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
>
> attached base packages:
> [1] datasets  parallel  utils     stats     graphics  grDevices methods
> base
>
> other attached packages:
> [1] showtext_0.9-5    showtextdb_3.0    sysfonts_0.8.8    data.table_1.14.6
> nlme_3.1-160      MASS_7.3-58.1
>
> loaded via a namespace (and not attached):
> [1] compiler_4.2.2  tools_4.2.2     grid_4.2.2      lattice_0.20-45
> R 4.2.2 GUI 1.79 Big Sur ARM build (8160)
>
> On Mon, Jan 9, 2023 at 5:25 PM David Novgorodsky <
> david.novgorodsky using gmail.com> wrote:
>
> > Hi all,
> >
> > First post, and my apologies if this was addressed already elsewhere, but
> > did not seem so to me. This post is (I think) purely about the
> > behavior of sessionInfo()
> > after I switch the BLAS to Apple's Accelerate vecLib.
> >
> > I installed R 4.2.2 on macOS Monterey 12.6.2 (with an M1 chip)
> > successfully. I run sessionInfo() with the following result:
> >
> > R version 4.2.2 (2022-10-31)
> >
> > Platform: aarch64-apple-darwin20 (64-bit)
> >
> > Running under: macOS Monterey 12.6.2
> >
> >
> >
> > Matrix products: default
> >
> > BLAS:
> >
> > /Library/Frameworks/R.framework/Versions/4.2-arm64/Resources/lib/libRblas.0.dylib
> >
> > LAPACK:
> >
> > /Library/Frameworks/R.framework/Versions/4.2-arm64/Resources/lib/libRlapack.dylib
> >
> >
> >
> > locale:
> >
> > [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
> >
> >
> >
> > attached base packages:
> >
> > [1] stats     graphics  grDevices utils     datasets  methods   base
> >
> >
> >
> > loaded via a namespace (and not attached):
> >
> > [1] compiler_4.2.2
> >
> > And then I run a small piece of test code (taken from somewhere, sorry,
> > can't recall where):
> >
> > N <- 20000
> > M <- 2000
> > X <- matrix(rnorm(N*M),N)
> > system.time(crossprod(X))
> >
> > with result
> >
> > > system.time(crossprod(X))
> > user  system  elapsed
> > 49.471  0.082  49.553
> >
> > Then I change my BLAS (using the vecLib supplied as part of the R
> > installation package), e.g., in the Terminal app:
> >
> > cd /Library/Frameworks/R.framework/Resources/lib
> > ln -sf libRblas.vecLib.dylib libRblas.dylib
> >
> > Afterwards, I restart R. Re-running the small piece of test code above
> > yields
> >
> > > system.time(crossprod(X))
> > user  system  elapsed
> > 0.339  0.015  0.197
> >
> > which suggests to me that the switch to vecLib did, indeed, succeed.
> >
> > However, sessionInfo() does something unexpected -- it no longer reports
> > anything for the BLAS row:
> >
> > R version 4.2.2 (2022-10-31)
> >
> > Platform: aarch64-apple-darwin20 (64-bit)
> >
> > Running under: macOS Monterey 12.6.2
> >
> >
> >
> > Matrix products: default
> >
> > LAPACK:
> >
> > /Library/Frameworks/R.framework/Versions/4.2-arm64/Resources/lib/libRlapack.dylib
> >
> >
> >
> > locale:
> >
> > [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
> >
> >
> >
> > attached base packages:
> >
> > [1] stats     graphics  grDevices utils     datasets  methods   base
> >
> >
> >
> > loaded via a namespace (and not attached):
> >
> > [1] compiler_4.2.2
> >
> > Anyone have any leads on whether a) this is a problem, and b) how to fix it
> > (if so)? Seems this has been the case at least for a couple of years, at
> > least based on an only tangentially related past thread (link here
> > <https://stat.ethz.ch/pipermail/r-sig-mac/2020-November/013794.html>)
> > where
> > the responder implicitly shows the same thing -- faster matrix
> > multiplication, but not reporting of BLAS in sessionInfo().
> >
> > Thanks,
> > David
> >
> >         [[alternative HTML version deleted]]
> >
> > _______________________________________________
> > R-SIG-Mac mailing list
> > R-SIG-Mac using r-project.org
> > https://stat.ethz.ch/mailman/listinfo/r-sig-mac
> >
>
>         [[alternative HTML version deleted]]
>
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