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