diff options
| author | Ludovic Courtès <ludo@gnu.org> | 2021-03-14 15:05:30 +0100 |
|---|---|---|
| committer | Ludovic Courtès <ludo@gnu.org> | 2021-03-21 23:41:01 +0100 |
| commit | 9da5ec7099b992a8969a17627548cd341c01bd90 (patch) | |
| tree | 82fa6307254029d42c3af67878c5f89dbdbc7164 /guix/narinfo.scm | |
| parent | 5f9b28b231e17749d14a1b95ae9cad68d7315a1e (diff) | |
substitute: Choose compression method based on past CPU usage.
This stems from the observation that substitute download can be
CPU-bound when high-speed networks are in use:
https://lists.gnu.org/archive/html/guix-devel/2020-12/msg00177.html
* guix/narinfo.scm (decompresses-faster?): New procedure.
(narinfo-best-uri): Add #:fast-decompression?.
* guix/scripts/substitute.scm (%prefer-fast-decompression?): New
variable.
(call-with-cpu-usage-monitoring): New procedure.
(with-cpu-usage-monitoring): New macro.
(display-narinfo-data, process-substitution): Pass #:fast-decompression?
to 'narinfo-best-uri'.
(process-substitution): Wrap 'restore-file' call in
'with-cpu-usage-monitoring'. Set '%prefer-fast-decompression?'.
Diffstat (limited to 'guix/narinfo.scm')
| -rw-r--r-- | guix/narinfo.scm | 27 |
1 files changed, 23 insertions, 4 deletions
diff --git a/guix/narinfo.scm b/guix/narinfo.scm index 2d06124017..72e0f75fda 100644 --- a/guix/narinfo.scm +++ b/guix/narinfo.scm @@ -1,5 +1,5 @@ ;;; GNU Guix --- Functional package management for GNU -;;; Copyright © 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org> +;;; Copyright © 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org> ;;; Copyright © 2014 Nikita Karetnikov <nikita@karetnikov.org> ;;; Copyright © 2018 Kyle Meyer <kyle@kyleam.com> ;;; @@ -297,9 +297,21 @@ this is a rough approximation." (_ (or (string=? compression2 "none") (string=? compression2 "gzip"))))) -(define (narinfo-best-uri narinfo) +(define (decompresses-faster? compression1 compression2) + "Return true if COMPRESSION1 generally has a higher decompression throughput +than COMPRESSION2." + (match compression1 + ("none" #t) + ("zstd" #t) + ("gzip" (string=? compression2 "lzip")) + (_ #f))) + +(define* (narinfo-best-uri narinfo #:key fast-decompression?) "Select the \"best\" URI to download NARINFO's nar, and return three values: -the URI, its compression method (a string), and the compressed file size." +the URI, its compression method (a string), and the compressed file size. +When FAST-DECOMPRESSION? is true, prefer substitutes with faster +decompression (typically zstd) rather than substitutes with a higher +compression ratio (typically lzip)." (define choices (filter (match-lambda ((uri compression file-size) @@ -321,6 +333,13 @@ the URI, its compression method (a string), and the compressed file size." (compresses-better? compression1 compression2)))) (_ #f))) ;we can't tell - (match (sort choices file-size<?) + (define (speed<? c1 c2) + (match c1 + ((uri1 compression1 . _) + (match c2 + ((uri2 compression2 . _) + (decompresses-faster? compression2 compression1)))))) + + (match (sort choices (if fast-decompression? (negate speed<?) file-size<?)) (((uri compression file-size) _ ...) (values uri compression file-size)))) |