Changes between Version 34 and Version 35 of IrqPriorities

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Author:
nettings (IP: 80.139.178.182)
Timestamp:
10/20/10 05:43:41 (6 years ago)
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  • IrqPriorities

    v34 v35  
    147147=== 4. Get the jackd priority Just Right(tm) === 
    148148 
    149 Now that all hardware-related priorities are settled, you can increase your jackd priority. Obviously, it does not make sense to raise it above the IRQ handlers we need for audio. But it makes a lot of sense to set it higher than the standard tasklet value, which is FF/50 on most systems. {{{60}}} will be a good value, because it leaves enough room to insert other stuff later, if necessary. But {{{51}}} will perform the same - remember these are relative numbers used for sorting a task queue, nothing more. 
    150  
    151 Use jackd's -P parameter, or set the priority value in qjackctl accordingly. Afterwards, you can verify your settings: 
    152 {{{ 
    153 hoppetosse:~ # ps -eLo pid,cls,rtprio,pri,nice,cmd | grep -i "FF" 
    154 }}} 
     149Now that all hardware-related priorities are settled, you can increase your jackd priority. Obviously, it does not make sense to raise it above the IRQ handlers we need for audio. But it makes a lot of sense to set it higher than the standard tasklet value, which is FF/50 on most systems. {{{70}}} would be a good value in most cases. Note that jackd will create some threads with higher and some with lower priorities for itself, and finally bestow RT privileges on its clients. It's generally helpful if these are still above the non-audio IRQ handlers, i.e. above 50. 
     150 
     151Use jackd's -P parameter, or set the priority value in qjackctl accordingly. The following command will show you all your SCHED_FIFO threads, sorted in decreasing priority: 
     152{{{ 
     153hoppetosse:~ # ps -eLo rtprio,cls,pid,pri,nice,cmd | grep "FF" | sort -r 
     154    99  FF    15 139   - [watchdog/0] 
     155    99  FF    14 139   - [posixcputmr/0] 
     156    99  FF     3 139   - [migration/0] 
     157    95  FF    12 135   - [sirq-hrtimer/0] 
     158    93  FF     5 133   - [sirq-timer/0] 
     159    91  FF    10 131   - [sirq-tasklet/0] 
     160    89  FF    11 129   - [sirq-sched/0] 
     161    87  FF    57 127   - [irq/8-rtc0] 
     162    85  FF   681 125   - [irq/16-yenta] 
     163    83  FF   713 123   - [irq/16-ohci1394] 
     164    81  FF    49 121   - [irq/19-ehci_hcd] 
     165    80  FF 16446 120   - /usr/bin/jackd -P70 -p1024 -t9999 -dfirewire -dhw:0 -r48000 -p2048 -n3 
     166    71  FF 16446 111   - /usr/bin/jackd -P70 -p1024 -t9999 -dfirewire -dhw:0 -r48000 -p2048 -n3 
     167    70  FF 16446 110   - /usr/bin/jackd -P70 -p1024 -t9999 -dfirewire -dhw:0 -r48000 -p2048 -n3 
     168    70  FF 16446 110   - /usr/bin/jackd -P70 -p1024 -t9999 -dfirewire -dhw:0 -r48000 -p2048 -n3 
     169    69  FF 16446 109   - /usr/bin/jackd -P70 -p1024 -t9999 -dfirewire -dhw:0 -r48000 -p2048 -n3 
     170    65  FF 16579 105   - /usr/local/lib/ardour2/ardour-2.8.11 
     171    65  FF  4161 105   - qjackctl 
     172    50  FF   710  90   - [irq/22-Intel IC] 
     173    50  FF   701  90   - [irq/23-Intel IC] 
     174    50  FF   698  90   - [irq/17-mmc0] 
     175    50  FF   678  90   - [irq/21-ipw2200] 
     176    50  FF   247  90   - [irq/16-i915] 
     177    50  FF    55  90   - [irq/1-i8042] 
     178    50  FF    54  90   - [irq/12-i8042] 
     179    50  FF    53  90   - [irq/19-uhci_hcd] 
     180    50  FF    52  90   - [irq/18-uhci_hcd] 
     181    50  FF    51  90   - [irq/17-uhci_hcd] 
     182    50  FF    50  90   - [irq/16-uhci_hcd] 
     183    50  FF    44  90   - [irq/15-ata_piix] 
     184    50  FF    43  90   - [irq/14-ata_piix] 
     185    50  FF    29  90   - [irq/9-acpi] 
     186    49  FF    13  89   - [sirq-rcu/0] 
     187    49  FF     9  89   - [sirq-block-iopo] 
     188    49  FF     8  89   - [sirq-block/0] 
     189    49  FF     7  89   - [sirq-net-rx/0] 
     190    49  FF     6  89   - [sirq-net-tx/0] 
     191    49  FF     4  89   - [sirq-high/0] 
     192     9  FF 16579  49   - /usr/local/lib/ardour2/ardour-2.8.11 
     193     1  FF 16446  41   - /usr/bin/jackd -P70 -p1024 -t9999 -dfirewire -dhw:0 -r48000 -p2048 -n3 
     194     1  FF 16446  41   - /usr/bin/jackd -P70 -p1024 -t9999 -dfirewire -dhw:0 -r48000 -p2048 -n3 
     195     1  FF    17  41   - [events/0] 
     196     -  TS 17282  19   0 grep FF 
     197}}} 
     198Note how the jack clients (ardour and qjackctl in this case) rank above the mundane IRQ handlers. At the bottom, you will see low-priority RT threads of jackd and ardour. Leave these alone - we should assume that the programmers know what they are doing. 
     199 
    155200 
    156201=== 5. (optional) Find a good slot for your external USB disk ===