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Bug#723566: marked as done (mdcfg: Set guaranteed resync speed to zero to accelerate install)

Your message dated Sat, 05 Oct 2013 17:07:11 +0000
with message-id <E1VSVJv-0007Lo-4Y@franck.debian.org>
and subject line Bug#723566: fixed in mdcfg 1.45
has caused the Debian Bug report #723566,
regarding mdcfg: Set guaranteed resync speed to zero to accelerate install
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what this
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immediately.)


-- 
723566: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=723566
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems
--- Begin Message --- 
Package: mdcfg
Severity: wishlist
Tags: d-i patch

Hello,

from benchmarks in bug #722898 it has emerged that blockdev-wipe is approx. 20%
faster when the guaranteed md resync speed [*] is zero, meaning that userspace
I/O will always be scheduled ahead of resync I/O. The default setting enforces
1000kB/s resync I/O before userspace requests are honoured. Although setting
aside 1MB/s for resync doesn't sound like much, this can translate to a loss of
10-20MB/s for userspace requests, presumably due to competition for disk
read/write heads. I assume that changing this setting will also bring speed
gains for the package installation phase, that's why I'm proposing a patch (cf.
attachment) to alter the setting whenever md devices are detected.

Bottom line: The proposed patch gives userspace full I/O priority, but md raid
resync will use whatever I/O bandwith that is not required by userspace.

Cheers,
Thiemo

[*] set via /proc/sys/dev/raid/speed_limit_min



-- System Information:
Debian Release: 7.1
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'proposed-updates'), (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 3.2.0-4-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

>From 086c51a14dbbc8868461c41820d712b9158994ae Mon Sep 17 00:00:00 2001
From: Thiemo Nagel <thiemo.nagel@gmail.com>
Date: Tue, 17 Sep 2013 14:51:59 +0200
Subject: [PATCH] Set guaranteed resync speed to zero to accelerate install

blockdev-wipe is approx. 20% faster that way (cf. bug #722898)
and I'd expect that there'll be similar improvements in the
package installation phase.
---
 mdcfg.sh |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mdcfg.sh b/mdcfg.sh
index 506e58c..2e3c9f7 100755
--- a/mdcfg.sh
+++ b/mdcfg.sh
@@ -430,6 +430,11 @@ if ! [ -e /proc/mdstat ] || ! [ -d /dev/md ]; then
 		exit 0
 	fi
 
+	# Speed up installation by de-priorizing (not stopping) array resync
+	if [ -w /proc/sys/dev/raid/speed_limit_min ]; then
+		echo 0 > /proc/sys/dev/raid/speed_limit_min
+	fi
+
 	# Try to detect MD devices, and start them
 	# mdadm will fail if /dev/md does not already exist
 	mkdir -p /dev/md
-- 
1.7.10.4

--- End Message ---
--- Begin Message --- 
Source: mdcfg
Source-Version: 1.45

We believe that the bug you reported is fixed in the latest version of
mdcfg, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 723566@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Christian Perrier <bubulle@debian.org> (supplier of updated mdcfg package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Format: 1.8
Date: Sat, 05 Oct 2013 18:38:37 +0200
Source: mdcfg
Binary: mdcfg mdcfg-utils
Architecture: source all
Version: 1.45
Distribution: unstable
Urgency: low
Maintainer: Debian Install System Team <debian-boot@lists.debian.org>
Changed-By: Christian Perrier <bubulle@debian.org>
Description: 
 mdcfg      - Configure MD devices (udeb)
 mdcfg-utils - Configure MD devices (udeb)
Closes: 723566
Changes: 
 mdcfg (1.45) unstable; urgency=low
 .
   [ Thiemo Nagel ]
   * Set guaranteed resync speed to zero to accelerate install
     Closes: #723566
 .
   [ Updated translations ]
   * Polish (pl.po) by Michał Kułach
Checksums-Sha1: 
 6c8a494419b11b76e3412f3332c6e416c32d58db 1634 mdcfg_1.45.dsc
 629fbe29be081fce34477130a31b774e19f5092f 169254 mdcfg_1.45.tar.gz
 109a233964abd831e223f0d8ad544a8dcfc5e3f4 4232 mdcfg_1.45_all.udeb
 95d127ef9fea21d1311caa90df099fe96030d4d8 156832 mdcfg-utils_1.45_all.udeb
Checksums-Sha256: 
 cd3828d9794f3adc6ec04f50d3fb76ce4dd5ac6b43be64e18d26d23d3aed4ad1 1634 mdcfg_1.45.dsc
 15e271b4b36de9d1d52118c59413fd3bfef78cc40974474decd30b7172346e71 169254 mdcfg_1.45.tar.gz
 4b731fc6cf91cae742728e017151ed64b7c745ae99f8ab432fe0aa6d4d1dafb7 4232 mdcfg_1.45_all.udeb
 00c608b72c142707f7fada253be40c88eca465ed87be7adcbb82d3dde973513f 156832 mdcfg-utils_1.45_all.udeb
Files: 
 3282284687eb17e1bf3c2199bd34e21a 1634 debian-installer optional mdcfg_1.45.dsc
 008598ed6bc4eefa0c437fdd658466a0 169254 debian-installer optional mdcfg_1.45.tar.gz
 925c0eaec48607764503d5acfe241428 4232 debian-installer optional mdcfg_1.45_all.udeb
 f3b4a8a30a48996d56adf19bc355ebcf 156832 debian-installer optional mdcfg-utils_1.45_all.udeb

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--- End Message ---
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