diff options
| -rw-r--r-- | doc/guix.texi | 61 | ||||
| -rw-r--r-- | guix/transformations.scm | 204 | ||||
| -rw-r--r-- | tests/transformations.scm | 35 |
3 files changed, 300 insertions, 0 deletions
diff --git a/doc/guix.texi b/doc/guix.texi index 354eead02b..b72a3d1263 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -11015,6 +11015,67 @@ available options and a synopsis (these options are not shown in the @table @code +@cindex performance, tuning code +@cindex optimization, of package code +@cindex tuning, of package code +@cindex SIMD support +@cindex tunable packages +@cindex package multi-versioning +@item --tune[=@var{cpu}] +Use versions of the packages marked as ``tunable'' optimized for +@var{cpu}. When @var{cpu} is @code{native}, or when it is omitted, tune +for the CPU on which the @command{guix} command is running. + +Valid @var{cpu} names are those recognized by the underlying compiler, +by default the GNU Compiler Collection. On x86_64 processors, this +includes CPU names such as @code{nehalem}, @code{haswell}, and +@code{skylake} (@pxref{x86 Options, @code{-march},, gcc, Using the GNU +Compiler Collection (GCC)}). + +As new generations of CPUs come out, they augment the standard +instruction set architecture (ISA) with additional instructions, in +particular instructions for single-instruction/multiple-data (SIMD) +parallel processing. For example, while Core2 and Skylake CPUs both +implement the x86_64 ISA, only the latter supports AVX2 SIMD +instructions. + +The primary gain one can expect from @option{--tune} is for programs +that can make use of those SIMD capabilities @emph{and} that do not +already have a mechanism to select the right optimized code at run time. +Packages that have the @code{tunable?} property set are considered +@dfn{tunable packages} by the @option{--tune} option; a package +definition with the property set looks like this: + +@lisp +(package + (name "hello-simd") + ;; ... + + ;; This package may benefit from SIMD extensions so + ;; mark it as "tunable". + (properties '((tunable? . #t)))) +@end lisp + +Other packages are not considered tunable. This allows Guix to use +generic binaries in the cases where tuning for a specific CPU is +unlikely to provide any gain. + +Tuned packages are built with @code{-march=@var{CPU}}; under the hood, +the @option{-march} option is passed to the actual wrapper by a compiler +wrapper. Since the build machine may not be able to run code for the +target CPU micro-architecture, the test suite is not run when building a +tuned package. + +To reduce rebuilds to the minimum, tuned packages are @emph{grafted} +onto packages that depend on them (@pxref{Security Updates, grafts}). +Thus, using @option{--no-grafts} cancels the effect of @option{--tune}. + +We call this technique @dfn{package multi-versioning}: several variants +of tunable packages may be built, one for each CPU variant. It is the +coarse-grain counterpart of @dfn{function multi-versioning} as +implemented by the GNU tool chain (@pxref{Function Multiversioning,,, +gcc, Using the GNU Compiler Collection (GCC)}). + @item --with-source=@var{source} @itemx --with-source=@var{package}=@var{source} @itemx --with-source=@var{package}@@@var{version}=@var{source} diff --git a/guix/transformations.scm b/guix/transformations.scm index 5ae1977cb2..c43c00cdd3 100644 --- a/guix/transformations.scm +++ b/guix/transformations.scm @@ -18,9 +18,11 @@ ;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>. (define-module (guix transformations) + #:use-module ((guix config) #:select (%system)) #:use-module (guix i18n) #:use-module (guix store) #:use-module (guix packages) + #:use-module (guix build-system) #:use-module (guix profiles) #:use-module (guix diagnostics) #:autoload (guix download) (download-to-store) @@ -29,6 +31,7 @@ #:autoload (guix upstream) (package-latest-release upstream-source-version upstream-source-signature-urls) + #:autoload (guix cpu) (current-cpu cpu->gcc-architecture) #:use-module (guix utils) #:use-module (guix memoization) #:use-module (guix gexp) @@ -49,6 +52,9 @@ #:export (options->transformation manifest-entry-with-transformations + tunable-package? + tuned-package + show-transformation-options-help %transformation-options)) @@ -419,6 +425,181 @@ the equal sign." obj) obj))) +(define tuning-compiler + (mlambda (micro-architecture) + "Return a compiler wrapper that passes '-march=MICRO-ARCHITECTURE' to the +actual compiler." + (define wrapper + #~(begin + (use-modules (ice-9 match)) + + (define* (search-next command + #:optional + (path (string-split (getenv "PATH") + #\:))) + ;; Search the next COMMAND on PATH, a list of + ;; directories representing the executable search path. + (define this + (stat (car (command-line)))) + + (let loop ((path path)) + (match path + (() + (match command + ("cc" (search-next "gcc")) + (_ #f))) + ((directory rest ...) + (let* ((file (string-append + directory "/" command)) + (st (stat file #f))) + (if (and st (not (equal? this st))) + file + (loop rest))))))) + + (match (command-line) + ((command arguments ...) + (match (search-next (basename command)) + (#f (exit 127)) + (next + (apply execl next + (append (cons next arguments) + (list (string-append "-march=" + #$micro-architecture)))))))))) + + (define program + (program-file (string-append "tuning-compiler-wrapper-" micro-architecture) + wrapper)) + + (computed-file (string-append "tuning-compiler-" micro-architecture) + (with-imported-modules '((guix build utils)) + #~(begin + (use-modules (guix build utils)) + + (define bin (string-append #$output "/bin")) + (mkdir-p bin) + + (for-each (lambda (program) + (symlink #$program + (string-append bin "/" program))) + '("cc" "gcc" "clang" "g++" "c++" "clang++"))))))) + +(define (build-system-with-tuning-compiler bs micro-architecture) + "Return a variant of BS, a build system, that ensures that the compiler that +BS uses (usually an implicit input) can generate code for MICRO-ARCHITECTURE, +which names a specific CPU of the target architecture--e.g., when targeting +86_64 MICRO-ARCHITECTURE might be \"skylake\". If it does, return a build +system that builds code for MICRO-ARCHITECTURE; otherwise raise an error." + (define %not-hyphen + (char-set-complement (char-set #\-))) + + (define lower + (build-system-lower bs)) + + (define (lower* . args) + ;; The list of CPU names supported by the '-march' option of C/C++ + ;; compilers is specific to each compiler and version thereof. Rather + ;; than pass '-march=MICRO-ARCHITECTURE' as is to the compiler, possibly + ;; leading to an obscure build error, check whether the compiler is known + ;; to support MICRO-ARCHITECTURE. If not, bail out. + (let* ((lowered (apply lower args)) + (architecture (match (string-tokenize (bag-system lowered) + %not-hyphen) + ((arch _ ...) arch))) + (compiler (any (match-lambda + ((label (? package? p) . _) + (and (assoc-ref (package-properties p) + 'compiler-cpu-architectures) + p)) + (_ #f)) + (bag-build-inputs lowered)))) + (unless compiler + (raise (formatted-message + (G_ "failed to determine which compiler is used")))) + + (let ((lst (assoc-ref (package-properties compiler) + 'compiler-cpu-architectures))) + (unless lst + (raise (formatted-message + (G_ "failed to determine whether ~a supports ~a") + (package-full-name compiler) + micro-architecture))) + (unless (member micro-architecture + (or (assoc-ref lst architecture) '())) + (raise (formatted-message + (G_ "compiler ~a does not support micro-architecture ~a") + (package-full-name compiler) + micro-architecture)))) + + (bag + (inherit lowered) + (build-inputs + ;; Arrange so that the compiler wrapper comes first in $PATH. + `(("tuning-compiler" ,(tuning-compiler micro-architecture)) + ,@(bag-build-inputs lowered)))))) + + (build-system + (inherit bs) + (lower lower*))) + +(define (tuned-package p micro-architecture) + "Return package P tuned for MICRO-ARCHITECTURE." + (package + (inherit p) + (build-system + (build-system-with-tuning-compiler (package-build-system p) + micro-architecture)) + (arguments + ;; The machine building this package may or may not be able to run code + ;; for MICRO-ARCHITECTURE. Because of that, skip tests; they are run for + ;; the "baseline" variant anyway. + (substitute-keyword-arguments (package-arguments p) + ((#:tests? _ #f) #f))) + + (properties + `((cpu-tuning . ,micro-architecture) + + ;; Remove the 'tunable?' property so that 'package-tuning' does not + ;; call 'tuned-package' again on this one. + ,@(alist-delete 'tunable? (package-properties p)))))) + +(define (tunable-package? package) + "Return true if package PACKAGE is \"tunable\"--i.e., if tuning it for the +host CPU is worthwhile." + (assq 'tunable? (package-properties package))) + +(define package-tuning + (mlambda (micro-architecture) + "Return a procedure that maps the given package to its counterpart tuned +for MICRO-ARCHITECTURE, a string suitable for GCC's '-march'." + (define rewriting-property + (gensym " package-tuning")) + + (package-mapping (lambda (p) + (cond ((assq rewriting-property (package-properties p)) + p) + ((assq 'tunable? (package-properties p)) + (info (G_ "tuning ~a for CPU ~a~%") + (package-full-name p) micro-architecture) + (package/inherit p + (replacement (tuned-package p micro-architecture)) + (properties `((,rewriting-property . #t) + ,@(package-properties p))))) + (else + p))) + (lambda (p) + (assq rewriting-property (package-properties p))) + #:deep? #t))) + +(define (transform-package-tuning micro-architectures) + "Return a procedure that, when " + (match micro-architectures + ((micro-architecture _ ...) + (let ((rewrite (package-tuning micro-architecture))) + (lambda (obj) + (if (package? obj) + (rewrite obj) + obj)))))) + (define (transform-package-with-debug-info specs) "Return a procedure that, when passed a package, set its 'replacement' field to the same package but with #:strip-binaries? #f in its 'arguments' field." @@ -601,6 +782,7 @@ are replaced by their latest upstream version." (with-commit . ,transform-package-source-commit) (with-git-url . ,transform-package-source-git-url) (with-c-toolchain . ,transform-package-toolchain) + (tune . ,transform-package-tuning) (with-debug-info . ,transform-package-with-debug-info) (without-tests . ,transform-package-tests) (with-patch . ,transform-package-patches) @@ -640,6 +822,28 @@ are replaced by their latest upstream version." (parser 'with-git-url)) (option '("with-c-toolchain") #t #f (parser 'with-c-toolchain)) + (option '("tune") #f #t + (lambda (opt name arg result . rest) + (define micro-architecture + (match arg + ((or #f "native") + (unless (string=? (or (assoc-ref result 'system) + (%current-system)) + %system) + (leave (G_ "\ +building for ~a instead of ~a, so tuning cannot be guessed~%") + (assoc-ref result 'system) %system)) + + (cpu->gcc-architecture (current-cpu))) + ("generic" #f) + (_ arg))) + + (apply values + (if micro-architecture + (alist-cons 'tune micro-architecture + result) + (alist-delete 'tune result)) + rest))) (option '("with-debug-info") #t #f (parser 'with-debug-info)) (option '("without-tests") #t #f diff --git a/tests/transformations.scm b/tests/transformations.scm index 09839dc1c5..8db85b4305 100644 --- a/tests/transformations.scm +++ b/tests/transformations.scm @@ -38,12 +38,14 @@ #:use-module (guix utils) #:use-module (guix git) #:use-module (guix upstream) + #:use-module (guix diagnostics) #:use-module (gnu packages) #:use-module (gnu packages base) #:use-module (gnu packages busybox) #:use-module (ice-9 match) #:use-module (srfi srfi-1) #:use-module (srfi srfi-26) + #:use-module (srfi srfi-34) #:use-module (srfi srfi-64)) @@ -465,6 +467,39 @@ `((with-latest . "foo"))))) (package-version (t p))))) +(test-equal "options->transformation, tune" + '(cpu-tuning . "superfast") + (let* ((p0 (dummy-package "p0")) + (p1 (dummy-package "p1" + (inputs `(("p0" ,p0))) + (properties '((tunable? . #t))))) + (p2 (dummy-package "p2" + (inputs `(("p1" ,p1))))) + (t (options->transformation '((tune . "superfast")))) + (p3 (t p2))) + (and (not (package-replacement p3)) + (match (package-inputs p3) + ((("p1" tuned)) + (match (package-inputs tuned) + ((("p0" p0)) + (and (not (package-replacement p0)) + (assq 'cpu-tuning + (package-properties + (package-replacement tuned))))))))))) + +(test-assert "options->transformations, tune, wrong micro-architecture" + (let ((p (dummy-package "tunable" + (properties '((tunable? . #t))))) + (t (options->transformation '((tune . "nonexistent-superfast"))))) + ;; Because GCC used by P's build system does not support + ;; '-march=nonexistent-superfast', we should see an error when lowering + ;; the tuned package. + (guard (c ((formatted-message? c) + (member "nonexistent-superfast" + (formatted-message-arguments c)))) + (package->bag (t p)) + #f))) + (test-equal "options->transformation + package->manifest-entry" '((transformations . ((without-tests . "foo")))) (let* ((p (dummy-package "foo")) |