Package: guix-patches;
Reported by: Efraim Flashner <efraim <at> flashner.co.il>
Date: Wed, 22 Jul 2020 18:12:01 UTC
Severity: normal
Tags: patch
Done: Efraim Flashner <efraim <at> flashner.co.il>
Bug is archived. No further changes may be made.
Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):
From: Efraim Flashner <efraim <at> flashner.co.il> To: guix-patches <at> gnu.org Cc: Efraim Flashner <efraim <at> flashner.co.il> Subject: [PATCH] services: Add zram-device-service. Date: Wed, 22 Jul 2020 21:10:25 +0300
* 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-device-configuration->udev-string): New
test.
---
doc/guix.texi | 45 +++++++++++++++++++++++++
gnu/services/linux.scm | 73 +++++++++++++++++++++++++++++++++++++++-
tests/services/linux.scm | 29 ++++++++++++++++
3 files changed, 146 insertions(+), 1 deletion(-)
diff --git a/doc/guix.texi b/doc/guix.texi
index 8696a9b554..f656c31fab 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -27127,6 +27127,51 @@ 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{disksize} (default @var{"0"})
+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{2G}.
+@item @code{comp_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{mem_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..7073a06cd7 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 <at> gmail.com>
;;; Copyright © 2020 Brice Waegeneire <brice <at> waegenei.re>
+;;; Copyright © 2020 Efraim Flashner <efraim <at> 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-disksize
+ zram-device-configuration-comp_algorithm
+ zram-device-configuration-mem_limit
+ zram-device-configuration-priority
+ zram-device-service-type))
;;;
@@ -177,3 +187,64 @@ 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?
+ (disksize zram-device-configration-disksize
+ (default "0")) ; string
+ (comp_algorithm zram-device-configuration-comp_algorithm
+ (default "lzo")) ; string
+ (mem_limit zram-device-configuration-mem_limit
+ (default "0")) ; string
+ (priority zram-device-configuration-priority
+ (default "-1"))) ; string
+
+(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> disksize comp_algorithm mem_limit priority)
+ (string-append
+ "KERNEL==\"zram0\", "
+ "ATTR{comp_algorithm}=\"" comp_algorithm "\" "
+ (if (not (equal? "0" disksize))
+ (string-append "ATTR{disksize}=\"" disksize "\" ")
+ "")
+ (if (not (equal? "0" mem_limit))
+ (string-append "ATTR{mem_limit}=\"" mem_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 " 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..828aa86bd6 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 <at> gmail.com>
+;;; Copyright © 2020 Efraim Flashner <efraim <at> flashner.co.il>
;;;
;;; This file is part of GNU Guix.
;;;
@@ -54,4 +55,32 @@
"-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
+ (disksize "2G")
+ (comp_algorithm "zstd")
+ (mem_limit "1G")
+ (priority "42")))
+
+(test-equal "zram-device-configuration->udev-string"
+ "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
+ (disksize "1G")
+ (comp_algorithm "lz4")))
+
+(test-equal "zram-device-configuration->udev-string"
+ "KERNEL==\"zram0\", ATTR{comp_algorithm}=\"lz4\" ATTR{disksize}=\"1G\" 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))
+
(test-end "linux-services")
--
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