[LAU] Focusrite Saffire Pro 40 - reliable?

Ralf Mardorf ralf.mardorf at alice-dsl.net
Sun Mar 1 16:28:45 UTC 2015


If tweaks do work, seems to depend to the hardware, BIOS update, Linux
driver etc..

For the ICE cards I can use 256/2/48000 without xruns, the HDSP card
can't be used lower than 256/2/48000 and even then or with
higher latencies, it still cause xruns.

Keyboard mini din, mouse USB, since the mini din mouse didn't work with
some Linux installs anymore.

AMD Athlon dual-core 2.1 GHz, 4 GiB RAM.

I didn't use the the uname -r kernel below for serious audio work, but
other x86_64 and x86 RTs.

For MIDI I use HR timer, but I can't use it for audio.

Nowadays I use the HDSP for audio and the ICE cards for MIDI. If I
don't need MIDI, I disable the ICE cards.

For audio nothing changes when changing PCI/PCIe slots or using a NVIDI
card instead of the integrated ATI graphics, it just has got impact to
the intervals, when MIDI jitter happens, but even for MIDI it doesn't
make a big difference. 




[rocketmouse at archlinux ~]$ uname -rm
3.10.61-rt65-1-rt-lts x86_64
[rocketmouse at archlinux ~]$
cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor performance
performance
[rocketmouse at archlinux ~]$ cat /usr/local/sbin/tuning
#!/bin/bash

# /usr/local/sbin/tuning - Arch Linux
# 2013/Apr/05

### http://www.mythtv.org/wiki/PCI_Latency
###
http://wiki.linuxmusicians.com/doku.php?id=system_configuration#pci_bus_latency

### Bluetooth
#service bluetooth stop

### Network
#service network-manager stop
#service networking stop # does cause serious issues
#modprobe -r r8169 # Ethernet NIC driver

### TerraTec EWX 24/96
#modprobe -r snd_ice1712

### Others
modprobe -r firewire-ohci
modprobe -r firewire_core
#service cups stop
modprobe -r ppdev # parallel port
modprobe -r lp    # printer

### Unbinding devices
echo -n "0000:00:13.2" > /sys/bus/pci/drivers/ohci_hcd/unbind
echo -n "0000:00:13.4" > /sys/bus/pci/drivers/ohci_hcd/unbind

### Log file
l="/var/log/tuning.log"
#echo "$ lspci -v                       "  > $l
#lspci -v                                 >> $l
#echo                                     >> $l
echo "# service rtirq status           "  > $l
service rtirq status                     >> $l
echo "# grep 18: /proc/interrupts"       >> $l
grep 18: /proc/interrupts                >> $l
echo                                     >> $l
echo -n $(date)" - "$(uname -r)" - "     >> $l
cat /etc/issue                           >> $l
echo -e
"\n########################################################################\n" ;
cat $l

exit 0
[rocketmouse at archlinux ~]$
diff /usr/local/sbin/tuning /usr/local/sbin/tuning-rice 
3c3
< # /usr/local/sbin/tuning - Arch Linux
---
> # /usr/local/sbin/tuning-rice - Arch Linux  
18c18
< #modprobe -r snd_ice1712
---
> modprobe -r snd_ice1712  
[rocketmouse at archlinux ~]$ grep music /etc/fstab
/dev/sda11				  /mnt/music
ext3	  noatime,defaults  0
2 /dev/sdb12				  /home/music
ext4	  noatime,defaults  0 2
[rocketmouse at archlinux ~]$ service
rtirq status

  PID CLS RTPRIO  NI PRI %CPU STAT COMMAND	
   44 FF      90   - 130  0.0 S    irq/8-rtc0	
  199 FF      85   - 125  0.0 S    irq/18-snd_hdsp	
  206 FF      80   - 120  0.0 S    irq/20-snd_ice1	
  213 FF      79   - 119  0.0 S    irq/21-snd_ice1	
   78 FF      75   - 115  0.0 S    irq/19-ehci_hcd	
   81 FF      75   - 115  0.0 S    irq/16-ohci_hcd	
   94 FF      74   - 114  0.0 S    irq/17-ohci_hcd	
  100 FF      73   - 113  0.0 S    irq/17-ohci_hcd	
   42 FF      70   - 110  0.0 S    irq/1-i8042	
   30 FF      50   -  90  0.0 S    irq/9-acpi	
   61 FF      50   -  90  0.0 S    irq/42-radeon	
   82 FF      50   -  90  0.0 S    irq/14-pata_ati	
   83 FF      50   -  90  0.0 S    irq/15-pata_ati	
   88 FF      50   -  90  0.0 S    irq/22-ahci	
  185 FF      50   -  90  0.0 S    irq/7-parport0	
  371 FF      50   -  90  0.0 S    irq/43-enp3s0	
    3 FF       1   -  41  0.4 S    ksoftirqd/0	
   19 FF       1   -  41  0.5 S    ksoftirqd/1	

[rocketmouse at archlinux ~]$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: HDSPMx579bcc [RME AIO_579bcc], device 0: RME AIO [RME AIO]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: EWX2496 [TerraTec EWX24/96], device 0: ICE1712 multi [ICE1712
multi] Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: EWX2496_1 [TerraTec EWX24/96], device 0: ICE1712 multi [ICE1712
multi] Subdevices: 1/1
  Subdevice #0: subdevice #0





RTIRQ_NAME_LIST

Regarding MIDI jitter caused by USB MIDI, there's no difference between
"usb" or making the USB port for the MIDI interface head of the USB
ports, perhaps for USB audio it has got noticeable impact.

[rocketmouse at archlinux ~]$ grep RTIRQ_NAME_LIST /etc/conf.d/rtirq
RTIRQ_NAME_LIST="rtc snd_hdsp snd_ice1 usb i8042"

JFTR the newer kernels assign individual IRQs to the graphics and
HDSP, but with older kernels they share the IRQ and not
sharing the IRQ anymore didn't improve anything.

Regards,
Ralf


More information about the Linux-audio-user mailing list