On 1/10/23 04:21, Kevin Ushey wrote:
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.
This is a feature of macOS since Big Sur 11.0.1, it has a dynamic-linker
cache of system libraries. The dynamic linker knows how to get the files
from the cache, but one cannot see them using regular file-based
utilities such as realpath. Yes, I think we can fall back to the
argument of realpath() when it returns ENOENT (but we know the library
should exist as we got it from the dynamic linker).
More here:
https://developer.apple.com/documentation/macos-release-notes/macos-big-sur-11_0_1-release-notes
I can reproduce the problem on my system. Now, what is interesting is
that when R is rebuilt after the libraries have already been installed
(e.g. when I use an uninstalled version of R linking to
libRblas.vecLib.dylib from an installed R-devel snapshot build), the
linker in the detection code reports:
/Library/Frameworks/R.framework/Versions/4.3-arm64/Resources/lib/libRblas.vecLib.dylib
which works fine with realpath(). But, when R is not re-built after the
library is re-installed, I see what has been reported. It is not clear
to me why the difference and possibly it means that, after the fix,
users would see a bit unpredictably one from these:
BLAS:
/Library/Frameworks/R.framework/Versions/4.3-arm64/Resources/lib/libRblas.vecLib.dylib
BLAS:
/System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/vecLib.framework/Versions/A/libBLAS.dylib
but that is still an improvement of what we get now and my intention was
that the detection code output would be interpreted by a human, anyway.
Best
Tomas
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 <clementfk...@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.novgorod...@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
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