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authorEfraim Flashner <efraim@flashner.co.il>2020-07-22 21:07:31 +0300
committerEfraim Flashner <efraim@flashner.co.il>2020-08-02 15:54:37 +0300
commit587e0d911dfff81647015e89847084b606e68f71 (patch)
tree63cd6575ccc64c18205f589f34badade4b804e8d
parenta05edef2ac692be8bf3033fe008b7c1b29f83123 (diff)
downloadguix-patches-587e0d911dfff81647015e89847084b606e68f71.tar
guix-patches-587e0d911dfff81647015e89847084b606e68f71.tar.gz
* gnu/services/linux.scm (<zram-device-configuration>): New record. (zram-device-service-type): New variable. * doc/guix.texi (Linux Services): Document it. * tests/services/linux.scm (zram-swap-device-test): New tests.
-rw-r--r--doc/guix.texi45
-rw-r--r--gnu/services/linux.scm81
-rw-r--r--tests/services/linux.scm37
3 files changed, 162 insertions, 1 deletions
diff --git a/doc/guix.texi b/doc/guix.texi
index c23ed8d715..f9cb7f204b 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -27283,6 +27283,51 @@ parameters, can be done as follow:
@end lisp
@end deffn
+@cindex zram
+@cindex compressed swap
+@cindex Compressed RAM-based block devices
+@subsubheading Zram Device Service
+
+The Zram device service provides a compressed swap device in system
+memory. The Linux Kernel documentation has more information about
+@uref{https://www.kernel.org/doc/html/latest/admin-guide/blockdev/zram.html,zram}
+devices.
+
+@deffn {Scheme Variable} zram-device-service-type
+This service creates the zram block device, formats it as swap and
+enables it as a swap device. The service's value is a
+@code{zram-device-configuration} record.
+
+@deftp {Data Type} zram-device-configuration
+This is the data type representing the configuration for the zram-device
+service.
+
+@table @asis
+@item @code{size} (default @var{"1G"})
+This is the amount of space you wish to provide for the zram device. It
+accepts a string and can be a number of bytes or use a suffix, eg.:
+@var{"512M"} or @var{1024000}.
+@item @code{compression-algorithm} (default @var{'lzo})
+This is the compression algorithm you wish to use. It is difficult to
+list all the possible compression options, but common ones supported by
+Guix's Linux Libre Kernel include @var{'lzo}, @var{'lz4} and @var{'zstd}.
+@item @code{memory-limit} (default @var{0})
+This is the maximum amount of memory which the zram device can use.
+Setting it to '0' disables the limit. While it is generally expected
+that compression will be 2:1, it is possible that uncompressable data
+can be written to swap and this is a method to limit how much memory can
+be used. It accepts a string and can be a number of bytes or use a
+suffix, eg.: @var{"2G"}.
+@item @code{priority} (default @var{-1})
+This is the priority of the swap device created from the zram device.
+@code{swapon} accepts values between -1 and 32767, with higher values
+indicating higher priority. Higher priority swap will generally be used
+first.
+@end table
+
+@end deftp
+@end deffn
+
@node Hurd Services
@subsection Hurd Services
diff --git a/gnu/services/linux.scm b/gnu/services/linux.scm
index 12934c2084..ec42663a11 100644
--- a/gnu/services/linux.scm
+++ b/gnu/services/linux.scm
@@ -1,6 +1,7 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2020 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;; Copyright © 2020 Brice Waegeneire <brice@waegenei.re>
+;;; Copyright © 2020 Efraim Flashner <efraim@flashner.co.il>
;;;
;;; This file is part of GNU Guix.
;;;
@@ -22,6 +23,7 @@
#:use-module (guix records)
#:use-module (guix modules)
#:use-module (gnu services)
+ #:use-module (gnu services base)
#:use-module (gnu services shepherd)
#:use-module (gnu packages linux)
#:use-module (srfi srfi-1)
@@ -42,7 +44,15 @@
earlyoom-configuration-send-notification-command
earlyoom-service-type
- kernel-module-loader-service-type))
+ kernel-module-loader-service-type
+
+ zram-device-configuration
+ zram-device-configuration?
+ zram-device-configuration-size
+ zram-device-configuration-compression-algorithm
+ zram-device-configuration-memory-limit
+ zram-device-configuration-priority
+ zram-device-service-type))
;;;
@@ -177,3 +187,72 @@ representation."
(compose concatenate)
(extend append)
(default-value '())))
+
+
+;;;
+;;; Kernel module loader.
+;;;
+
+(define-record-type* <zram-device-configuration>
+ zram-device-configuration make-zram-device-configuration
+ zram-device-configuration?
+ (size zram-device-configration-size
+ (default "1G")) ; string or integer
+ (compression-algorithm zram-device-configuration-compression-algorithm
+ (default 'lzo)) ; symbol
+ (memory-limit zram-device-configuration-memory-limit
+ (default 0)) ; string or integer
+ (priority zram-device-configuration-priority
+ (default -1))) ; integer
+
+(define (zram-device-configuration->udev-string config)
+ "Translate a <zram-device-configuration> into a string which can be
+placed in a udev rules file."
+ (match config
+ (($ <zram-device-configuration> size compression-algorithm memory-limit priority)
+ (string-append
+ "KERNEL==\"zram0\", "
+ "ATTR{comp_algorithm}=\"" (symbol->string compression-algorithm) "\" "
+ (if (not (or (equal? "0" size)
+ (equal? 0 size)))
+ (string-append "ATTR{disksize}=\"" (if (number? size)
+ (number->string size)
+ size)
+ "\" ")
+ "")
+ (if (not (or (equal? "0" memory-limit)
+ (equal? 0 memory-limit)))
+ (string-append "ATTR{mem_limit}=\"" (if (number? memory-limit)
+ (number->string memory-limit)
+ memory-limit)
+ "\" ")
+ "")
+ "RUN+=\"/run/current-system/profile/sbin/mkswap /dev/zram0\" "
+ "RUN+=\"/run/current-system/profile/sbin/swapon "
+ (if (not (equal? -1 priority))
+ (string-append "--priority " (number->string priority) " ")
+ "")
+ "/dev/zram0\"\n"))))
+
+(define %zram-device-config
+ `("modprobe.d/zram.conf"
+ ,(plain-file "zram.conf"
+ "options zram num_devices=1")))
+
+(define (zram-device-udev-rule config)
+ (file->udev-rule "99-zram.rules"
+ (plain-file "99-zram.rules"
+ (zram-device-configuration->udev-string config))))
+
+(define zram-device-service-type
+ (service-type
+ (name 'zram)
+ (default-value (zram-device-configuration))
+ (extensions
+ (list (service-extension kernel-module-loader-service-type
+ (const (list "zram")))
+ (service-extension etc-service-type
+ (const (list %zram-device-config)))
+ (service-extension udev-service-type
+ (compose list zram-device-udev-rule))))
+ (description "Creates a zram swap device.")))
diff --git a/tests/services/linux.scm b/tests/services/linux.scm
index 8ad119c49f..e2cd191e48 100644
--- a/tests/services/linux.scm
+++ b/tests/services/linux.scm
@@ -1,5 +1,6 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2020 Maxim Cournoyer <maxim.cournoyer@gmail.com>
+;;; Copyright © 2020 Efraim Flashner <efraim@flashner.co.il>
;;;
;;; This file is part of GNU Guix.
;;;
@@ -54,4 +55,40 @@
"-N" "python \"/some/path/notify-all-users.py\"")
(earlyoom-configuration->command-line-args %earlyoom-configuration-sample))
+
+;;;
+;;; Zram swap device.
+;;;
+
+(define zram-device-configuration->udev-string
+ (@@ (gnu services linux) zram-device-configuration->udev-string))
+
+(define %zram-swap-device-test-1
+ (zram-device-configuration
+ (size "2G")
+ (compression-algorithm 'zstd)
+ (memory-limit "1G")
+ (priority 42)))
+
+(test-equal "zram-swap-device-test-1"
+ "KERNEL==\"zram0\", ATTR{comp_algorithm}=\"zstd\" ATTR{disksize}=\"2G\" ATTR{mem_limit}=\"1G\" RUN+=\"/run/current-system/profile/sbin/mkswap /dev/zram0\" RUN+=\"/run/current-system/profile/sbin/swapon --priority 42 /dev/zram0\"\n"
+ (zram-device-configuration->udev-string %zram-swap-device-test-1))
+
+(define %zram-swap-device-test-2
+ (zram-device-configuration
+ (size 1048576) ; 1M
+ (compression-algorithm 'lz4)))
+
+(test-equal "zram-swap-device-test-2"
+ "KERNEL==\"zram0\", ATTR{comp_algorithm}=\"lz4\" ATTR{disksize}=\"1048576\" RUN+=\"/run/current-system/profile/sbin/mkswap /dev/zram0\" RUN+=\"/run/current-system/profile/sbin/swapon /dev/zram0\"\n"
+ (zram-device-configuration->udev-string %zram-swap-device-test-2))
+
+(define %zram-swap-device-test-3
+ (zram-device-configuration
+ (memory-limit (* 512 1000))))
+
+(test-equal "zram-swap-device-test-3"
+ "KERNEL==\"zram0\", ATTR{comp_algorithm}=\"lzo\" ATTR{disksize}=\"1G\" ATTR{mem_limit}=\"512000\" RUN+=\"/run/current-system/profile/sbin/mkswap /dev/zram0\" RUN+=\"/run/current-system/profile/sbin/swapon /dev/zram0\"\n"
+ (zram-device-configuration->udev-string %zram-swap-device-test-3))
+
(test-end "linux-services")