[LAU] Kernel 2.6.39

[Ralf Mardorf]

On Thu, 2011-06-23 at 12:00 +0000,
linux-audio-user-request at lists.linuxaudio.org wrote:
> 
> Message: 1
> Date: Thu, 23 Jun 2011 08:42:15 +0100
> From: Rui Nuno Capela <rncbc at rncbc.org>
> Subject: Re: [LAU] Kernel 2.6.39
> To: linux-audio-user at lists.linuxaudio.org
> Message-ID: <4E02EE57.7020003 at rncbc.org>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> On 06/23/2011 07:17 AM, Ralf Mardorf wrote:
> >
> > I used the config from the self-build kernel 2.6.33.9-rt31 and run
> > oldconfig only to configure 2.6.39. I didn't make music until now using
> > this kernel. Yes, I wish to "emulate" the PREEMPT_RT, since common
> > PREEMPT only kernels never did, what I needed.
> >
> > What do I need to set?
> >
> > $ cat config-2.6.39.1 | grep PREEMPT
> > CONFIG_TREE_PREEMPT_RCU=y
> > CONFIG_PREEMPT_RCU=y
> > CONFIG_PREEMPT_NOTIFIERS=y
> > # CONFIG_PREEMPT_NONE is not set
> > # CONFIG_PREEMPT_VOLUNTARY is not set
> > CONFIG_PREEMPT=y
> >
> > IIUC this is correct?!
> >
> 
> yes.
> 
> and don't forget to add "threadirqs" to your kernel bootloader 
> line--only then you'll get "rtirq" to do its magic as it used to do on a 
> genuine -rt kernel.
> 
> 
> >
> > PS: SCHED_FF?
> >
> 
> SCHED_FF is a process/thread attribute, not a kernel configuration 
> option--jack does that for you when told to run with realtime scheduling.
> 
> 
> byee
> -- 
> rncbc aka Rui Nuno Capela
> rncbc at rncbc.org
> 
> 
> ------------------------------
> 
> Message: 2
> Date: Thu, 23 Jun 2011 00:59:29 -0700 (PDT)
> From: James Warden <warjamy at yahoo.com>
> Subject: Re: [LAU] Kernel 2.6.39
> To: linux-audio-user at lists.linuxaudio.org
> Message-ID:
> 	<1308815969.6124.YahooMailClassic at web39321.mail.mud.yahoo.com>
> Content-Type: text/plain; charset=us-ascii
> 
> 
> 
> --- On Thu, 6/23/11, Rui Nuno Capela <rncbc at rncbc.org> wrote:
> 
> > From: Rui Nuno Capela <rncbc at rncbc.org>
> > Subject: Re: [LAU] Kernel 2.6.39
> > To: linux-audio-user at lists.linuxaudio.org
> > Date: Thursday, June 23, 2011, 3:42 AM
> > On 06/23/2011 07:17 AM, Ralf Mardorf
> > wrote:
> > >
> > > I used the config from the self-build kernel
> > 2.6.33.9-rt31 and run
> > > oldconfig only to configure 2.6.39. I didn't make
> > music until now using
> > > this kernel. Yes, I wish to "emulate" the PREEMPT_RT,
> > since common
> > > PREEMPT only kernels never did, what I needed.
> > >
> > > What do I need to set?
> > >
> > > $ cat config-2.6.39.1 | grep PREEMPT
> > > CONFIG_TREE_PREEMPT_RCU=y
> > > CONFIG_PREEMPT_RCU=y
> > > CONFIG_PREEMPT_NOTIFIERS=y
> > > # CONFIG_PREEMPT_NONE is not set
> > > # CONFIG_PREEMPT_VOLUNTARY is not set
> > > CONFIG_PREEMPT=y
> > >
> > > IIUC this is correct?!
> > >
> > 
> > yes.
> > 
> > and don't forget to add "threadirqs" to your kernel
> > bootloader 
> > line--only then you'll get "rtirq" to do its magic as it
> > used to do on a 
> > genuine -rt kernel.
> > 
> 
> And remember to use /etc/default/grub to have this threadirqs boot option permanent:
> 
> /etc/default/grub : GRUB_CMDLINE_LINUX="threadirqs"
> 
> if you are too lazy to compile / recompile /etc, just use the liquorix debian kernel (http://liquorix.net/)
> 
> I use that one (kernel compiled with CONFIG_PREEMPT=y, threadirqs at boot). It does wonders! I tried the cyclictest mentioned by Rui and I got some quite outstanding numbers on my system.
> 
> 
> (However, the liquorix kernel is not PAE, which prevents the use of more than 4GB RAM for 32bit systems with more than 4GB of physical RAM)
> 
> J.

spinymouse at debian:/boot$ less config-2.6.39.1 | grep
ONFIG_IRQ_FORCED_THREADING
CONFIG_IRQ_FORCED_THREADING=y

So I don't need to re-build the kernel?

PAE is irrelevant for me, hence I'm using 64-bit architecture.

Hm, less seems to be less comfortable, I hope I'm allowed to use cat
instead.

$ less /etc/default/grub ... needs to copies, so I fall back to cut, it
needs just one copy.
$ cat /etc/default/grub
# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
#   info -f grub -n 'Simple configuration'

GRUB_DEFAULT=0
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet"
GRUB_CMDLINE_LINUX=""

So I need to add

GRUB_CMDLINE_LINUX="threadirqs"

?

Thanks,

Ralf

OT:
> Oberhausen at 11:30
Julien, this is the Ruhrgebiet city I'm living :D.