The different realtime kernels

[Ralf Mardorf]

On Thu, 2010-09-30 at 12:58 -0400, Ronan Jouchet wrote:
> On Thu, Sep 30, 2010 at 11:45 AM, Ralf Mardorf
> <ralf.mardorf at alice-dsl.net> wrote:
> > Why does Ubuntu Studio comes without PREEMPT RT, but just PREEMPT?!
> > This is my intension.
> >
> > FWIW, I'm a professional audio and video engineer and did program oldish
> > computers and I'm missing hard real-time for modern PCs. Even the
> > kernel-rt isn't able to do hard real-time, so I don't understand why
> > Ubuntu Studio does prefer a kernel without rt-patch. Today the rt-patch
> > isn't good enough and any kernel without this patch is useless for
> > multimedia production.
> >
> > So a misunderstanding ;)!
> 
> Hello Ralf,
> 
> You keep coming back to -rt/-realtime, but nobody ever questioned
> their greatness. I trust you when you mention -rt is the ideal
> solution in your heavy MIDI use case, and I would also *love* a
> properly maintained -rt kernel in Studio.
> 
> Now, whether we want it or not, the facts are:
> - Preparing -realtime (vanilla+rtpatch) or -rt
> (vanilla+ubuntusauce+rtpatch) is a lot of work and there are no
> resources for this
> - On the contrary, -lowlatency (generic with some config tweaks) means
> performance tradeoff, _but_ could happen in a PPA (maybe even in the
> archives in Natty) because it is less of a maintenance hell
> 
> You mention you have some custom built kernels, so if you feel like
> helping maintaining -realtime/-rt, by all means step in, talk to
> Alessio and make it happen. But insisting again and again on -rt and
> -realtime without considering the possibilities is only going to
> discourage him from working on the feasible options.
> 
> He tries to propose sustainable options and the only echoes are
> negative, without much questioning. What are the results of your own
> tests with -lowlatency? What kind of performance drop have you met on
> one of your heavy setups? How much latency lost, on which kind of
> machine / firewire card?
> 
> Ronan

Hi Ronan :)

I marked your email and will come back to it ASAP. At the moment the
influenza gained the upper hand.

I guess it's not that important what issues I had when using the PREEMPT
kernel, there were issues and I didn't noticed that it was a PREEMPT,
but a PREEMPT RT kernel, when I posted something, including uname -a at
LAD or JACK mailing list. Somebody else noticed it. I might do another
test, or search the archives, but I would prefer trying to compile and
build a package for a kernel-rt again on my Ubuntu Studio and post the
package for 64-bit or ask because of trouble, if the compiling should
fail, resp. the startup when booting the kernel should fail.

Perhaps I could try to compile a kernel-rt at the weekend. I suspect
issues for the startup regarding to X, but I'm not sure.

To be continued ... probably this weekend ... if I don't answer until
the week after next, please remember me to compile a kernel-rt and to
post the messages I get when booting the kernel-rt from the
repositories.

Today I don't wish to test anything.

I've got two PCI Envy24 cards, Terratec EWX 24/96, a NVidia 7200 GS + an
onboard Radeon X1250-based graphics. The mobo is a M2A-VM HDMI and

suse11-2:/home/spinymouse11.2 # hwinfo --cpu
01: None 00.0: 10103 CPU                                        
  [Created at cpu.301]
  Unique ID: rdCR.j8NaKXDZtZ6
  Hardware Class: cpu
  Arch: X86-64
  Vendor: "AuthenticAMD"
  Model: 15.107.2 "AMD Athlon(tm) X2 Dual Core Processor BE-2350"
  Features:
fpu,vme,de,pse,tsc,msr,pae,mce,cx8,apic,sep,mtrr,pge,mca,cmov,pat,pse36,clflush,mmx,fxsr,sse,sse2,ht,syscall,nx,mmxext,fxsr_opt,rdtscp,lm,3dnowext,3dnow,rep_good,extd_apicid,pni,cx16,lahf_lm,cmp_legacy,svm,extapic,cr8_legacy,3dnowprefetch
  Clock: 1000 MHz
  BogoMips: 1999.85
  Cache: 512 kb
  Units/Processor: 2
  Config Status: cfg=new, avail=yes, need=no, active=unknown

02: None 01.0: 10103 CPU
  [Created at cpu.301]
  Unique ID: wkFv.j8NaKXDZtZ6
  Hardware Class: cpu
  Arch: X86-64
  Vendor: "AuthenticAMD"
  Model: 15.107.2 "AMD Athlon(tm) X2 Dual Core Processor BE-2350"
  Features:
fpu,vme,de,pse,tsc,msr,pae,mce,cx8,apic,sep,mtrr,pge,mca,cmov,pat,pse36,clflush,mmx,fxsr,sse,sse2,ht,syscall,nx,mmxext,fxsr_opt,rdtscp,lm,3dnowext,3dnow,rep_good,extd_apicid,pni,cx16,lahf_lm,cmp_legacy,svm,extapic,cr8_legacy,3dnowprefetch
  Clock: 1000 MHz
  BogoMips: 1999.85
  Cache: 512 kb
  Units/Processor: 2
  Config Status: cfg=new, avail=yes, need=no, active=unknown
suse11-2:/home/spinymouse11.2 # hwinfo --memory
01: None 00.0: 10102 Main Memory                                
  [Created at memory.61]
  Unique ID: rdCR.CxwsZFjVASF
  Hardware Class: memory
  Model: "Main Memory"
  Memory Range: 0x00000000-0x7fedffff (rw)
  Memory Size: 2 GB
  Config Status: cfg=new, avail=yes, need=no, active=unknown

In addition I do have an USB swissonic MIDI device, but it's not
connected, because it's better to use the Envy24 PCI card MPU.

I try to get a better sound card, but at the moment this is my setup.
HDMI and on-board sound disabled.

Cheers!

Ralf