Hi :) I'm new to the list. Regarding to hw MIDI jitter, I'm testing and comparing several Linux setups.
Here is a rough summary of my latest thread on LAD. I wonder what I need to do, to get a kernel-rt for Ubuntustudio 10.04? ........................................................................ Ubuntu Studio 10.04 amd64 $ uname -a Linux ubuntu 2.6.32-23-preempt #37-Ubuntu SMP PREEMPT Fri Jun 11 10:19:07 UTC 2010 x86_64 GNU/Linux $ alsa-midi-latency-test -Rrw=2 -o20:0 -i20:0 > alsa-midi-latency-test 0.0.3 > set_realtime_priority(SCHED_FIFO, 99).. done. > clock resolution: 0.000000001 s > SUCCESS best latency was 1.00 ms worst latency was 3.36 ms, which is great. 3.36 ms isn't great, but unusable to make music. ........................................................................ openSUSE 11.2 amd64 > uname -a Linux suse11-2 2.6.31.6-rt19 #1 SMP PREEMPT RT Wed Nov 18 16:59:26 CET 2009 x86_64 x86_64 x86_64 GNU/Linux > alsa-midi-latency-test -Rrw=2 -o16:0 -i16:0 > alsa-midi-latency-test 0.0.3 > set_realtime_priority(SCHED_FIFO, 99).. done. > clock resolution: 0.000000001 s > SUCCESS best latency was 0.99 ms worst latency was 1.05 ms, which is great. ........................................................................ PREEMPT vs PREEMPT RT and of course frequency scaling for an audio distro should be at performance by default, anyway, the frequency scaling isn't a big deal. I tried to boot the kernel-rt from the Ubuntu repositories and I tried to build a kernel-rt myself. If I try to boot kernel 2.6.31-11-rt or kernel 2.6.31-10-rt from the repositories I get 'mount: mounting none on /dev failed: No such device.' Regading to the web this might be, because of CONFIG_DEVTMPFS. # cat config-2.6.31-11-rt | grep CONFIG_DEVTMPFS # cat config-2.6.32-23-preempt | grep CONFIG_DEVTMPFS CONFIG_DEVTMPFS=y CONFIG_DEVTMPFS_MOUNT=y When I try to boot kernel 2.6.33-23-realtime from the repository I get 'ACPI: Expecting a [Reference] package element, found type 0'. At least this three kernel-rt from the repositories come with an initrd. The kernel I tried to build the way I usually build kernels for Ubuntu with success, is missing an initrd. $ cd /usr/src $ sudo synaptic I checked if those packages were installed: bin86 build-essential bzip2 fakeroot gcc kernel-package make libncurses5-dev $ wget ftp://ftp.kernel.org/pub/linux/kernel/v2.6/linux-2.6.33.5.tar.bz2 $ wget http://www.kernel.org/pub/linux/kernel/projects/rt/patch-2.6.33.5-rt23.bz2 $ tar xvjf linux-2.6.33.5.tar.bz2 $ rm linux-2.6.33.5.tar.bz2 $ mv linux-2.6.33.5 linux-2.6.33.5-rt23 $ ln -s linux-2.6.33.5-rt23 linux $ cd linux $ bunzip2 ../patch-2.6.33.5-rt23.bz2 $ patch -p1 < ../patch-2.6.33.5-rt23 $ rm ../patch-2.6.33.5-rt23 $ cp /boot/config-2.6.32-23-preempt .config $ make oldconfig 81 x Enter $ make menuconfig Edited from Generic-x86-64 to Opteron/Athlon64/Hammer/K8 Save an Alternate Configuration File $ make oldconfig Nothing to do $ make-kpkg clean $ export CONCURRENCY_LEVEL=2 This didn't work: $ make-kpkg --rootcmd fakeroot --initrd kernel-image kernel-headers kernel-source 50 minutes later make[5]: *** [drivers/staging/comedi/drivers/quatech_daqp_cs.o] Error 1 make[4]: *** [drivers/staging/comedi/drivers] Error 2 Hence I edited .config: $ cat .config | grep COMEDI CONFIG_COMEDI=m # CONFIG_COMEDI_DEBUG is not set CONFIG_COMEDI_PCI_DRIVERS=m CONFIG_COMEDI_PCMCIA_DRIVERS=m CONFIG_COMEDI_USB_DRIVERS=m $ gedit .config $ cat .config | grep COMEDI # CONFIG_COMEDI is not set # CONFIG_COMEDI_DEBUG is not set # CONFIG_COMEDI_PCI_DRIVERS is not set # CONFIG_COMEDI_PCMCIA_DRIVERS is not set # CONFIG_COMEDI_USB_DRIVERS is not set $ make oldconfig Nothing to do $ make-kpkg clean $ make-kpkg --rootcmd fakeroot --initrd kernel-image kernel-headers kernel-source Another 50 minutes later make[4]: *** [drivers/staging/pohmelfs/inode.o] Error 1 make[3]: *** [drivers/staging/pohmelfs] Error 2 Hence I edited .config: $ cat .config | grep POHMEL CONFIG_POHMELFS=m # CONFIG_POHMELFS_DEBUG is not set CONFIG_POHMELFS_CRYPTO=y $ gedit .config $ cat .config | grep POHMEL # CONFIG_POHMELFS is not set # CONFIG_POHMELFS_DEBUG is not set # CONFIG_POHMELFS_CRYPTO is not set $ make oldconfig Nothing to do $ make-kpkg clean Here it is ok: $ make-kpkg --rootcmd fakeroot --initrd kernel-image kernel-headers kernel-source 80 minutes later $ cd .. $ sudo dpkg -i linux-image-2.6.33.5-rt23_2.6.33.5-rt23-10.00.Custom_amd64.deb ........................................................................ When I tried to boot the kernel I got '[ 0.499322] ACPI: Expecting a [Reference] package element, found type 0 [ 0.811991] kernel panic - not syncing: VPS: Unable to mount root fs on unknown-block (0,0)' Any hints are welcome! Cheers! Ralf -- Ubuntu-Studio-users mailing list Ubuntu-Studio-users@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-studio-users
