My response only got sent to Fernando. Here it is for all of you to see :)
/Lars
---------- Forwarded message ----------
From: Lars-Erik Helander <lehswe(a)gmail.com>
Date: 2009/2/2
Subject: Re: [LAT] [LAU] Are RT-patches needed anymore? (Was Re: >=
2.6.27 RT ETA?)
To: Fernando Lopez-Lezcano <nando(a)ccrma.stanford.edu>
Fernando your elaborate response is highly appreciated, thanks!!
>> - Will "rtirq" make a difference on a non-RT-patched kernel system?
>
> No AFAIK. Non-rt patched kernels do not have irq processes running as
> separate SCHED_FIFO threads (which is what is tuned by rtirq).
>
This was my thought to.
>> - Do I need to assign rtprios explicitly to all my processes
>> (qjackctl, qsynth, ...) or is that "automagic"?
>
> Automagic. Jackd gives the proper priority to the clients (to the thread
> of the client that handles audio i/o)
>
I use "lmms" every now and then. I have never been able to get "lmms"
to work well with jack so I use it with ALSA as the audio driver. This
works fine though I can not use jack application simultaneously. So in
this case do I have to explicitly give "lmms" SCHED_FIFO and rtprio?
How (using chrt?) ?
>> I have close to 30 years experience in developing realtime systems and
>> has been using Linux for audio in various distribution the last two
>> years. Further I have built RT-kernel for couple of distributions
>> (this weekend I successfully built and ran a 2.6.28-rt kernel from the
>> new git tree :) ).
>
> Ah, I have not tried this yet! How did that work out? Any errors or
> problems on boot? How exactly did you go about building the whole thing?
>
About a week ago building from the git produced a kernel that did not
boot properly, actually it did not even build properly and my own
remedy for the build problem resulted in a kernel that was not able to
boot up properly. However building from the git this weekend produced
a well working kernel. Only problem found is the softirq.c bug that
has been around for a while (it makes USB MIDI keyboards etc not to
work - they are discovered but no MIDI events are received) so I had
to apply a patch for that problem.
Build procedure was very straightforward using the git url I cloned
the git and got myself a complete (already "patched" kernel source
tree) and it was just to do the normal "make oldconfig", "make
menuconfig" ... procedures.
>> However I have no experience in using newer non-RT
>> kernels but I am very interested to find out how well you can have
>> them work, especially since whenever you find a nice distro you can
>> not use it because the hazzle of building an RT-kernel for that
>> particular distro is so big :(.
>
> Planet CCRMA (http://ccrma.stanford.edu/planetccrma/software/) has rt
> patched kernels of the 2.6.26.8* flavor for fc9 (in the "testing"
> repository) and fc10, and should be easy to install (not an objective
> assessment, I created and maintain Planet CCRMA :-).
I have also sucsessfully built and used 2.6.26.8-rt13 with the Slitaz
(www.slitaz.org) distribution (the git kernel also works with that
distribution).
In order to use the kernel with my USB MIDI devices I had to apply the
above mentioned softirq.c patch.
/Lars
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Fernando Lopez-Lezcano wrote:
> On Fri, 2009-01-30 at 03:23 +0100, torbenh(a)gmx.de wrote:
>> On Thu, Jan 29, 2009 at 03:41:48PM -0800, Fernando Lopez-Lezcano wrote:
>>> On Tue, 2009-01-27 at 14:06 +0100, Peder Hedlund wrote:
>>>> Quoting Ken Restivo <ken(a)restivo.org>:
>>>>
>>>>> And here is the next installment in the saga of trying to get Ingo
>>>>> RT going on my Asus EEE.
>>>>>
>>>>> I successfully built and ran the 2.6.26.8-rt12 with the alsa_seq
>>>>> patch. It ran.
>>>>>
>>>>> The problem is that neither the Ethernet (atl1e) or wireless
>>>>> (rt2860sta) work. So I pretty much had to reboot back out of it
>>>>> immediately.
>>>> I've been running the standard kernel from openSUSE 11.0 on my Athlon
>>>> 2000+ and can get down to at least 5.3ms latency on an Audiophile 2496
>>>> using the limits.conf "trick".
>>>>
>>>> Do people really need lower latencies for music purposes or are we
>>>> just thinking "well, I needed the RT patch three years ago; I ain't
>>>> stopping now" ?
>>> It depends on your usage (this question seems to come up every couple of
>>> months lately). The current kernels are much better in low latency
>>> applications than three years ago. They are usable if you don't require
>>> "low" latencies (64 or 128 x 2). What you get also strongly depends on
>>> the hardware mix you have.
>>>
>>> If you want to use 64 or 128 frame periods (or less) you probably will
>>> need at rt patched kernel in most cases. Then again if an occasional
>>> xrun is not a problem then you would be fine with the stock kernel.
>> i am running with -p64 -n3 on an intel-hda with 2.6.28
>> of course internal cards have the greatest potential for lowlatencies.
>> so this might be unfair, compared to pci.
>
> Hmmm, I'm not sure, the load on pci itself by a soundcard should be
> nothing really hard. What would the internal card use? Would not that be
> pci or pci express anyway?
>
surely they are.
$ lspci | grep Audio
00:1b.0 Audio device: Intel Corporation 82801G (ICH7 Family) High
Definition Audio Controller (rev 02)
The RT patch does two things:
It allows to prioritize interrupts and it [almost] guarantees real-time
scheduling for a dedicated process or thread.
While the soundcard is low bandwith on the PCI bus, IRQ prio may still
be required to override HDD and [sometimes] graphics I/O; at least when
playing or recording many tracks. NTL, you can get a perfect x-run free
system without the RT patch; you can just not rely on it to be as x-run
free as a RT patched kernel ;)
>> and i havent really seen xruns which i could not relate to some
>> programm which wasnt RT-safe, and i am compiling stuff most of the day...
>> though perhaps i am not pushing the DSP load hard enough.
>>
>> i did not even turn preemptible RCU on.
>> the latency measurement instrumentation is also in 2.6.28 btw.
>
> Well, that's very good news then!
>
> I think the last time I tried to use a non-preempt was 2.6.27.x (maybe,
> I would have to double check). Playing 24 channels in ardour would
> result in xruns, not very often but they would happen, this is with
> 128x2 on an RME hdsp card runing on a quad core intel system. I should
> try again with the latest available.
I just booted into a vanilla 2.6.28.2 #1 SMP PREEMPT
right, there's no realtime patch, yet running jackd at 64 * 3 @48kSPS on
a HDA - ardour2 with 12 tracks, a couple of LADSPA effects and jamin
(lots of CPU!) - there's no xruns yet!
I'll be back in the studio in two weeks from now to test it with USB and
1394 devices. With <=2.6.24 kernels those were always working more
reliably that the HDA so I don't expect problems there.
BTW. with 2.6.28 I needed to
`echo -1 > /proc/sys/kernel/sched_rt_runtime_us`
or edit /etc/sysctl.conf and add
sys.kernel.sched_rt_runtime_us = -1
before JACK was able to acquire real-time privileges.
Here's my .config running running debian/lenny+sid on a Thinkpad X60s:
http://mir.dnsalias.com/_media/wiki/kernel/config-2.6.28.2.txt
robin
PS. I bumped into Linus at LCA: 2.6.27 still had various issues with the
"big kernel lock" in some modules - most notably vfat - but they should
be pretty much gone by now. YAY!
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Hi,
I want a system purely for audio production on my amd64. Mainly latest
ardour for audio, plus stuff for midi sequencing, effects, sound editing
etc. Visiting internet cafe to download source code for this stuff.
I've read about patching 2.6 kernels but had not realised it was
required.
Is 2.6.27.7 still flakey for realtime, is there a patch for it? Any
recommendations for kernel + patch for amd64?
I'm using a coverdisc of debian lenny as a minimal base system + xorg +
fluxbox (can't stomache gnome dependancies), am wondering if maybe a
better choice might be had, regarding development libraries included in
an ISO which would satisfy dependancies for building the s/w most
important (like ardour2.7, etc etc)?
Cheers,
James.
Hi,
There are some rumors about the lack of need for an RT patch with new
kernel, after 2.6.26.xx for making (realtime) music on GNU/Linux.
What is true about this?
Thanks in advance,
\r
< ------------ Původní zpráva ------------
< Od: krgn <k.gebbert(a)gmail.com>
< Předmět: Re: [LAT] build ALSA debian way
< Datum: 07.10.2008 04:26:20
< ----------------------------------------
< On Mon, Oct 6, 2008 at 7:18 PM, Jaromír Mikeš <mira.mikes(a)seznam.cz> wrote:
<
< >
< > < ------------ Původní zpráva ------------
< > < Od: krgn <k.gebbert(a)gmail.com>
< > < Předmět: Re: [LAT] build ALSA debian way
< > < Datum: 07.10.2008 03:28:09
< > < ----------------------------------------
< > < On Mon, Oct 6, 2008 at 4:19 PM, Jaromír Mikeš <mira.mikes(a)seznam.cz>
< > wrote:
< > <
< > < > Hi,
< > < >
< > < > I've compiled new kernel for me 2.6.24.7-rt20 which seems to have a
< > bug in
< > < > builded alsa modules (RME Digiface,Multiface).
< > < >
< > <
< > < yes that bit me too :)
< > <
< > <
< > < >
< > < > http://article.gmane.org/gmane.linux.alsa.user/29391/match=2.6.24
< > < >
< > < > I would like to upgrade alsa modules from 1.0.15 wich coming with
< > kernel
< > < > source to 1.0.17
< > < > I already builded new kernel without alsa modules and now I would like
< > to
< > < > build alsa from source.
< > < > I am using debian based distro so make a debian package would be best
< > for
< > < > me.
< > < >
< > < > Is there any way how to do it?
< > < > I didn't found any new howto which I dare to follow.
< > < >
< > <
< > < use module-assistant. you'll need the headers/sources for your kernel
< > < installed too.
< > <
< > < aptitude install module-assistant build-essentials
< > <
< > < then
< > <
< > < module-assitant to build and install debs for alsa and co.
< > <
< > < k
< > <
< > Thanks for answer,
< > actually I have already installed these packages and I've stopped on
< > module-assitant.
< > I was run:
< > #cd /alsa-driver-1.0.17
< > #m-a prepare alsa-driver-1.0.17
< >
< > It seems to run well.
< >
< > Now I am trying:
< > # m-a build
< > No package specified. STOP.
< >
< > I've tryed put some name for package:
< > #m-a build alsa-modules
< > alsa-modules, what is alsa-modules?
< >
< > Sorry for newbie like question, but reading man pages doesn't helps.
< >
<
< I think it should be:
<
< m-a build alsa-source
<
< if you have bash completion enabled it should show on typing the first
< couple of letters and pressing Tab
<
< cheers,
<
< k
<
Thanks for help,
I've got some error messages on the end of process, which I've saw quite often in last days.
There is probably some bug. My errors are very similar to that in report.
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=501417
cheers
mira
< ------------ Původní zpráva ------------
< Od: krgn <k.gebbert(a)gmail.com>
< Předmět: Re: [LAT] build ALSA debian way
< Datum: 07.10.2008 03:28:09
< ----------------------------------------
< On Mon, Oct 6, 2008 at 4:19 PM, Jaromír Mikeš <mira.mikes(a)seznam.cz> wrote:
<
< > Hi,
< >
< > I've compiled new kernel for me 2.6.24.7-rt20 which seems to have a bug in
< > builded alsa modules (RME Digiface,Multiface).
< >
<
< yes that bit me too :)
<
<
< >
< > http://article.gmane.org/gmane.linux.alsa.user/29391/match=2.6.24
< >
< > I would like to upgrade alsa modules from 1.0.15 wich coming with kernel
< > source to 1.0.17
< > I already builded new kernel without alsa modules and now I would like to
< > build alsa from source.
< > I am using debian based distro so make a debian package would be best for
< > me.
< >
< > Is there any way how to do it?
< > I didn't found any new howto which I dare to follow.
< >
<
< use module-assistant. you'll need the headers/sources for your kernel
< installed too.
<
< aptitude install module-assistant build-essentials
<
< then
<
< module-assitant to build and install debs for alsa and co.
<
< k
<
Thanks for answer,
actually I have already installed these packages and I've stopped on module-assitant.
I was run:
#cd /alsa-driver-1.0.17
#m-a prepare alsa-driver-1.0.17
It seems to run well.
Now I am trying:
# m-a build
No package specified. STOP.
I've tryed put some name for package:
#m-a build alsa-modules
alsa-modules, what is alsa-modules?
Sorry for newbie like question, but reading man pages doesn't helps.
mira
Hi,
I've compiled new kernel for me 2.6.24.7-rt20 which seems to have a bug in builded alsa modules (RME Digiface,Multiface).
http://article.gmane.org/gmane.linux.alsa.user/29391/match=2.6.24
I would like to upgrade alsa modules from 1.0.15 wich coming with kernel source to 1.0.17
I already builded new kernel without alsa modules and now I would like to build alsa from source.
I am using debian based distro so make a debian package would be best for me.
Is there any way how to do it?
I didn't found any new howto which I dare to follow.
Thanks for advice.
mira
Hi,
I was reading on some forums that there is possible to set different values.
What makes me confused.
Anyway thanks
Mira
< ------------ Původní zpráva ------------
< Od: Ismael Valladolid Torres <ivalladt(a)gmail.com>
< Předmět: Re: [LAT] Kernel log buffer size
< Datum: 02.10.2008 22:33:05
< ----------------------------------------
< On Thu, Oct 2, 2008 at 8:36 PM, Jaromír Mikeš <mira.mikes(a)seznam.cz> wrote:
< > What are right values for these processors?
<
< Most probably the default values are Ok unless you plan on kernel debugging.
<
< Cordially, Ismael
< --
< Ismael Valladolid Torres GnuPG key: DE721AF4
<
< SHS Polar (3.4.3) Google Talk/Jabber/MSN Messenger: ivalladt(a)gmail.com
< C/ Emilio Vargas 1 Jaiku/Twitter/Skype/Yahoo!: ivalladt
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< 28043 Madrid (Spain)
<
< T 0034915153817 http://lamediahostia.blogspot.com
< F 0034915153755 http://www.flickr.com/photos/ivalladt/
<
< The opinions expressed here represent my own and not those of my employer.
< Las opiniones expresadas representan las mías propias y no las de mi empresa.
<
<
<
Hello,
sorry for newbie like question, but I really can't find clear answer on my question.
What is right choice in: $ make xconfig -> "Processor type and features" ->"Processor family"
I've choose "Pentium Pro" for my Intel Core
Exist some chart? I am quite confused by this categories.
Thanks for help
Mira