Hello Guix,
I recently discovered that the FFTW library can do runtime cpu
detection. In order to do this, the package needs to be configured to
build SIMD "codelets", like how our 'fftw-avx' currently does. Then,
based on the instruction support detected at runtime, make those
kernels available to the fftw "planner" for execution.
I tested this on two systems: 1) system with sse2, and 2) system with
avx2. I configured the library with "--enable-sse2 --enable-avx
--enable-avx2", then ran the following on both systems:
1)
$ ./tests/bench --verbose=3 --verify 'ibcd11x7x6v10'
Planning ibcd11x7x6v10...
using plan_many_dft
estimate-planner time: 0.004355 s
using plan_many_dft
planner time: 0.035684 s
(dft-rank>=2/1
(dft-vrank>=1-x11/1
(dft-rank>=2/1
(dft-vrank>=1-x7/1
(dft-direct-6-x10 "n1bv_6_sse2"))
(dft-direct-7-x60 "n1bv_7_sse2")))
(dft-direct-11-x420 "n1bv_11_sse2"))
flops: 36800 add, 9700 mul, 26260 fma
estimated cost: 99057.699080, pcost = 115706.000000
ibcd11x7x6v10 4.33362e-16 7.27264e-16 8.46842e-16
2)
$ ./tests/bench --verbose=3 --verify 'ibcd11x7x6v10'
Planning ibcd11x7x6v10...
using plan_many_dft
estimate-planner time: 0.001485 s
using plan_many_dft
planner time: 0.025788 s
(dft-rank>=2/1
(dft-rank>=2/1
(dft-vrank>=1-x77/1
(dft-direct-6-x10 "n1bv_6_sse2"))
(dft-vrank>=1-x11/1
(dft-direct-7-x60 "n1bv_7_avx")))
(dft-direct-11-x420 "n1bv_11_avx"))
flops: 12280 add, 2810 mul, 6950 fma
estimated cost: 28996.283180, pcost = 40767.000000
ibcd11x7x6v10 2.24601e-07 3.90447e-07 2.42548e-07
The attached patch is a WIP.
--
Eric Bavier, Scientific Libraries, Cray Inc.
diff --git a/gnu/packages/algebra.scm b/gnu/packages/algebra.scm
index 2aa1777db..96c78ea81 100644
--- a/gnu/packages/algebra.scm
+++ b/gnu/packages/algebra.scm
@@ -533,17 +533,26 @@ a C program.")
(build-system gnu-build-system)
(arguments
'(#:configure-flags
- '("--enable-shared" "--enable-openmp" "--enable-threads")
- #:phases (alist-cons-before
- 'build 'no-native
- (lambda _
- ;; By default '-mtune=native' is used. However, that may
- ;; cause the use of ISA extensions (SSE2, etc.) that are
- ;; not necessarily available on the user's machine when
- ;; that package is built on a different machine.
- (substitute* (find-files "." "Makefile$")
- (("-mtune=native") "")))
- %standard-phases)))
+ `("--enable-shared" "--enable-openmp" "--enable-threads"
+ ,@(let ((system (or (%current-target-system) (%current-system))))
+ (cond
+ ((or (string-prefix? "x86_64" system)
+ (string-prefix? "i686" system))
+ ;; Enable AVX & co. for codelets. See details at:
+ ;; <http://fftw.org/fftw3_doc/Installation-on-Unix.html>.
+ '("--enable-avx" "--enable-avx2"
+ "--enable-avx512" "--enable-avx-128-fma"))
+ ((string-prefix? "aarch64" system)
+ '("--enable-neon" "--enable-armv8-cntvct-el0"))
+ ((string-prefix? "armv7" system)
+ '("--enable-neon" "--enable-armv7a-cntvct"))
+ ((string-prefix? "mips" system)
+ '("--enable-mips-zbus-timer"))))
+ ;; By default '-mtune=native' is used. However, that may cause the
+ ;; use of ISA extensions (e.g. AVX) that are not necessarily
+ ;; available on the user's machine when that package is built on a
+ ;; different machine.
+ "ax_cv_c_flags__mtune_native=no")))
(native-inputs `(("perl" ,perl)))
(home-page "http://fftw.org";)
(synopsis "Computing the discrete Fourier transform")
@@ -560,7 +569,7 @@ cosine/ sine transforms or DCT/DST).")
(arguments
(substitute-keyword-arguments (package-arguments fftw)
((#:configure-flags cf)
- `(cons "--enable-float" ,cf))))
+ `(cons "--enable-float" "--enable-sse" ,cf))))
(description
(string-append (package-description fftw)
" Single-precision version."))))
@@ -592,29 +601,6 @@ cosine/ sine transforms or DCT/DST).")
(base32
"0wsms8narnbhfsa8chdflv2j9hzspvflblnqdn7hw8x5xdzrnq1v"))))))
-(define-public fftw-avx
- (package
- (inherit fftw-3.3.7)
- (name "fftw-avx")
- (arguments
- (substitute-keyword-arguments (package-arguments fftw-3.3.7)
- ((#:configure-flags flags ''())
- ;; Enable AVX & co. See details at:
- ;; <http://fftw.org/fftw3_doc/Installation-on-Unix.html>.
- `(append '("--enable-avx" "--enable-avx2" "--enable-avx512"
- "--enable-avx-128-fma")
- ,flags))
- ((#:substitutable? _ #f)
- ;; To run the tests, we must have a CPU that supports all these
- ;; extensions. Since we cannot be sure that machines in the build
- ;; farm support them, disable substitutes altogether.
- #f)
- ((#:phases _)
- ;; Since we're not providing binaries, let '-mtune=native' through.
- '%standard-phases)))
- (synopsis "Computing the discrete Fourier transform (AVX2-optimized)")
- (supported-systems '("x86_64-linux"))))
-
(define-public java-la4j
(package
(name "java-la4j")
