Libguestfs - Jun 2010 - [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.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming blog: http://rwmj.wordpress.com
Fedora now supports 80 OCaml packages (the OPEN alternative to F#)
http://cocan.org/getting_started_with_ocaml_on_red_hat_and_fedora
-------------- next part --------------
>From 1253f577fa162b9170b22f3c543167aa99795920 Mon Sep 17 00:00:00 2001
From: Richard Jones <rjones at 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

On 07/06/10 15:33, Richard W.M. Jones wrote:
>> From 1253f577fa162b9170b22f3c543167aa99795920 Mon Sep 17 00:00:00 2001
> From: Richard Jones<rjones at 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(-)
ACK.

Matt
-- 
Matthew Booth, RHCA, RHCSS
Red Hat Engineering, Virtualisation Team

M:       +44 (0)7977 267231
GPG ID:  D33C3490
GPG FPR: 3733 612D 2D05 5458 8A8A 1600 3441 EA19 D33C 3490