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[Libguestfs] [PATCH] Use the noop scheduler inside the appliance.



The Wikipedia pages about schedulers are quite informative.  I don't
know _why_ this makes a difference, but it does seem to make a small
one.  Even though for a single process (guestfsd) it would seem that
the choice of scheduler should make no difference.

BTW the default scheduler in the guest is 'cfq'.

http://en.wikipedia.org/wiki/Noop_scheduler
http://en.wikipedia.org/wiki/CFQ

Rich.

-- 
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>From 1253f577fa162b9170b22f3c543167aa99795920 Mon Sep 17 00:00:00 2001
From: Richard Jones <rjones redhat com>
Date: Mon, 7 Jun 2010 15:29:31 +0100
Subject: [PATCH] Use the noop scheduler inside the appliance.

In my limited tests, this seems to make a small but noticable
difference, improving the performance of some straightforward
read operations by a little over 10%.

For more information see:
http://kbase.redhat.com/faq/docs/DOC-5428
---
 appliance/init |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/appliance/init b/appliance/init
index c622788..b8133ca 100755
--- a/appliance/init
+++ b/appliance/init
@@ -66,6 +66,9 @@ lvm vgchange -ay --ignorelockingfailure
 # Improve virtio-blk performance (RHBZ#509383).
 for f in /sys/block/vd*/queue/rotational; do echo 1 > $f; done
 
+# http://kbase.redhat.com/faq/docs/DOC-5428
+for f in /sys/block/[hsv]d*/queue/scheduler; do echo noop > $f; done
+
 # Keep these to enhance the usefulness of debug output.
 ls -l /dev
 cat /proc/mounts
-- 
1.6.6.1


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