Hello,

What is COW?
I figured out that every harddisk access is terrible for realtime behavior.
It doesn't matters if the system runs with or without aufs.

The solution is to decrease the priority of the harddisk interrupt and the 
thread that is writing the data.

My program has 16 threads and one low prior writes the data of a 3D 
Laserscanner onto the harddisk. It doesn't matters if the data is written to 
tmpfs or the real disk.


I'm using this script to decrease the priority of the harddisk interrupt:



#!/bin/sh

ps -ef | grep irq/15 | grep -v grep | awk '{ print $2 }' > /dev/null

if [ $? ==  '0' ]
then
        echo "irq/15 changed from -51 to -6"
        schedtool -F -p 5 `ps -ef | grep irq/15 | grep -v grep | awk '{ print 
$2 }'`
else
        echo -e "\033[31m"
        echo "hmm, are you working without Harddisk??"
        echo "or has it another IRQ as irq/15-ide1?"
        echo -e "\033[0m"
        
fi

-----Original Message-----
From: Jordi Pujol [mailto:jordipuj...@gmail.com] 
Sent: Dienstag, 17. August 2010 11:09
To: aufs-users@lists.sourceforge.net
Subject: Re: aufs does not compile with 2.6.33.5-rt23, error in 
fs/aufs/super.c:450

A Dimarts 17 Agost 2010 06:32:49, sf...@users.sourceforge.net va escriure:
> I will add the file aufs2-standalone.git/2.6.33.5-rt25.patch.

Hello,

Also works with other 2.6.33 realtime versions, I think the name could be more 
generic, i.e. 2.6.33-rt.patch

Aufs with realtime works fast when COW is on tmpfs, but when COW is on a 
disk partition, writing to it becomes very slow, and after a while the 
complete OS hangs,

I have tested the version rt25, and others also, all have the same problem,
in a Live system where the root filesystem is an aufs COW on a disk partition,

Here Is a Debian source package to build the last kernel that I used,

http://livenet.selfip.com/ftp/debian/linux-2.6/linux-2.6.33-7.rt29.jpp.3-lnet/

Regards,

Jordi Pujol

Live never ending Tale
GNU/Linux Live forever!
http://livenet.selfip.com

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