--- Begin Message ---
- To: Debian Bug Tracking System <submit@bugs.debian.org>
- Subject: mdcfg: Set guaranteed resync speed to zero to accelerate install
- From: Thiemo Nagel <thiemo.nagel@gmail.com>
- Date: Tue, 17 Sep 2013 15:52:20 +0200
- Message-id: <20130917135220.21660.99426.reportbug@kiste>
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
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