linuxaudio.org

Hi all,
I just built a threaded-irqs enabled 2.6.39.1 kernel and used cyclictest

to try to get an initial feeling of how good it might be. Cyclictest

tests scheduling delays of the kernel it is running on[*]. These tests

were run on a Fedora 13 T510 Lenovo laptop, with the ugly binary Nvidia

driver (caveat emptor).
In the menu:
   2.6.39.1 with threaded irqs and PREEMPT active

   2.6.33.13-rt31

   2.6.34.8-rt31 (a forward port of rt31 to 2.6.34)

   plain Fedora kernel (2.6.34.8-68.fc13.i686.PAE)
Now, before someone points it out, this is just a synthetic test that

measures scheduling latency, not a real audio application.
See below for details... (look at the "Avg:" and "Max:" latency values,

those are in microseconds)
Unless I have done something wrong, it looks like we have a long way to

go with regards to scheduling latency in anything other than 2.6.33 + rt

patches. But, with threaded irqs in 2.6.39 maybe the performance with

audio applications running under jack will be good anyway as we will be

able to tune irq processing. Seems to me unlikely. I have not tested

that yet.
Tests were done after a clean reboot, initially with the machine idle

and then while loading thunderbird with tons of emails and firefox with

tons of pages. No audio work.
YMMV...

-- Fernando
[*] https://rt.wiki.kernel.org/index.php/RT_PREEMPT_HOWTO
----------------------------------------------------------------------

LENOVO T510
----------------------------------------------------------------------

2.6.33.13-149.rt31.2.fc13.ccrma.i686.rtPAE

----------------------------------------------------------------------
$ while true ; do ./cyclictest -t1 -p 80 -n -i 10000 -l 10000 ; done

policy: fifo: loadavg: 0.02 0.20 0.11 1/405 7024
T: 0 ( 7024) P:80 I:10000 C:  10000 Min:      3 Act:   75 Avg:   54 Max:

     121

policy: fifo: loadavg: 0.08 0.17 0.10 2/405 7027
T: 0 ( 7026) P:80 I:10000 C:  10000 Min:      3 Act:   73 Avg:   75 Max:

     126

policy: fifo: loadavg: 0.01 0.12 0.09 1/405 7029
T: 0 ( 7029) P:80 I:10000 C:  10000 Min:      3 Act:   90 Avg:   49 Max:

     141

policy: fifo: loadavg: 0.37 0.21 0.12 1/405 7031
T: 0 ( 7031) P:80 I:10000 C:  10000 Min:      4 Act:   70 Avg:   76 Max:

     148

policy: fifo: loadavg: 0.27 0.21 0.12 1/405 7033
T: 0 ( 7033) P:80 I:10000 C:  10000 Min:      4 Act:   46 Avg:   73 Max:

     144

policy: fifo: loadavg: 0.15 0.20 0.12 1/405 7035
T: 0 ( 7035) P:80 I:10000 C:  10000 Min:      3 Act:   90 Avg:   77 Max:

     142

policy: fifo: loadavg: 0.07 0.15 0.11 2/405 7037
T: 0 ( 7037) P:80 I:10000 C:  10000 Min:      3 Act:   16 Avg:   71 Max:

     135

policy: fifo: loadavg: 0.05 0.12 0.10 1/405 7040
T: 0 ( 7039) P:80 I:10000 C:  10000 Min:      3 Act:   84 Avg:   72 Max:

     142

policy: fifo: loadavg: 0.01 0.08 0.08 1/405 7042
T: 0 ( 7042) P:80 I:10000 C:  10000 Min:      3 Act:  105 Avg:   51 Max:

     146

policy: fifo: loadavg: 0.00 0.05 0.07 1/406 7045
T: 0 ( 7044) P:80 I:10000 C:  10000 Min:      4 Act:   11 Avg:   50 Max:

     121

policy: fifo: loadavg: 0.07 0.06 0.07 1/406 7047
T: 0 ( 7047) P:80 I:10000 C:  10000 Min:      2 Act:   73 Avg:   76 Max:

     140

policy: fifo: loadavg: 0.01 0.04 0.06 1/406 7049
T: 0 ( 7049) P:80 I:10000 C:  10000 Min:      3 Act:   67 Avg:   70 Max:

     137

policy: fifo: loadavg: 0.02 0.04 0.06 1/406 7051
T: 0 ( 7051) P:80 I:10000 C:   9573 Min:      3 Act:   68 Avg:   47 Max:

     146

policy: fifo: loadavg: 0.02 0.04 0.06 1/406 7053
----------------------------------------------------------------------

2.6.34.8-68.fc13.i686.PAE

----------------------------------------------------------------------
$ while true ; do ./cyclictest -t1 -p 80 -n -i 10000 -l 10000 ; sleep

10; done

policy: fifo: loadavg: 0.20 0.33 0.15 1/298 2559
T: 0 ( 2521) P:80 I:10000 C:  10000 Min:      3 Act:   12 Avg:   36 Max:

     354

policy: fifo: loadavg: 0.34 0.30 0.16 1/332 2676
T: 0 ( 2583) P:80 I:10000 C:  10000 Min:      3 Act:   12 Avg:   31 Max:

    1749

policy: fifo: loadavg: 0.39 0.38 0.20 1/350 2835
T: 0 ( 2726) P:80 I:10000 C:  10000 Min:      2 Act:    9 Avg:   33 Max:

   12861

policy: fifo: loadavg: 0.11 0.29 0.18 2/350 2839
T: 0 ( 2838) P:80 I:10000 C:  10000 Min:      3 Act:   12 Avg:   43 Max:

     133

policy: fifo: loadavg: 0.02 0.19 0.16 1/348 2842
T: 0 ( 2842) P:80 I:10000 C:  10000 Min:      4 Act:   75 Avg:   48 Max:

   17789

policy: fifo: loadavg: 0.07 0.15 0.14 1/347 2858
T: 0 ( 2845) P:80 I:10000 C:  10000 Min:      4 Act:   56 Avg:   50 Max:

    1808

policy: fifo: loadavg: 0.18 0.15 0.14 1/347 2861
T: 0 ( 2861) P:80 I:10000 C:  10000 Min:      3 Act:   11 Avg:   52 Max:

     187

policy: fifo: loadavg: 0.34 0.19 0.15 1/345 2864
T: 0 ( 2864) P:80 I:10000 C:  10000 Min:      4 Act:   69 Avg:   46 Max:

     119

policy: fifo: loadavg: 0.39 0.28 0.19 1/346 2869
T: 0 ( 2867) P:80 I:10000 C:  10000 Min:      3 Act:   14 Avg:   27 Max:

     361

policy: fifo: loadavg: 0.10 0.20 0.17 1/347 2875
T: 0 ( 2872) P:80 I:10000 C:  10000 Min:      4 Act:   14 Avg:   31 Max:

     425

policy: fifo: loadavg: 0.01 0.13 0.15 1/346 2882
T: 0 ( 2879) P:80 I:10000 C:  10000 Min:      4 Act:   58 Avg:   55 Max:

     186

policy: fifo: loadavg: 0.09 0.12 0.13 1/346 2887
T: 0 ( 2885) P:80 I:10000 C:  10000 Min:      4 Act:   67 Avg:   50 Max:

     129

policy: fifo: loadavg: 0.10 0.12 0.13 1/347 2890
----------------------------------------------------------------------

2.6.39.1-1.threadirqs.1.fc14.ccrma.i686.PAE

----------------------------------------------------------------------
$ while true ; do ./cyclictest -t1 -p 80 -n -i 10000 -l 10000 ; sleep

10; done

policy: fifo: loadavg: 0.13 0.25 0.12 1/290 2279
T: 0 ( 2279) P:80 I:10000 C:  10000 Min:      5 Act:   42 Avg:   45 Max:

    1015

policy: fifo: loadavg: 0.64 0.36 0.18 1/338 2567
T: 0 ( 2299) P:80 I:10000 C:  10000 Min:      4 Act:   48 Avg:   44 Max:

    3124

policy: fifo: loadavg: 0.20 0.30 0.18 1/337 2583
T: 0 ( 2571) P:80 I:10000 C:  10000 Min:      3 Act:   43 Avg:   50 Max:

   10301

policy: fifo: loadavg: 0.07 0.22 0.16 2/341 2592
T: 0 ( 2586) P:80 I:10000 C:  10000 Min:      5 Act:   30 Avg:   46 Max:

   15227

policy: fifo: loadavg: 0.48 0.33 0.21 3/340 2602
T: 0 ( 2595) P:80 I:10000 C:  10000 Min:      4 Act:    7 Avg:   29 Max:

     992

policy: fifo: loadavg: 0.17 0.28 0.21 1/340 2613
T: 0 ( 2610) P:80 I:10000 C:  10000 Min:      3 Act:   15 Avg:   32 Max:

      99

policy: fifo: loadavg: 0.34 0.27 0.21 4/346 2660
T: 0 ( 2616) P:80 I:10000 C:  10000 Min:      3 Act:   14 Avg:   36 Max:

    1326

policy: fifo: loadavg: 0.14 0.25 0.22 2/342 2680
T: 0 ( 2665) P:80 I:10000 C:  10000 Min:      3 Act:   14 Avg:   38 Max:

     709

policy: fifo: loadavg: 0.18 0.24 0.22 1/342 2687
T: 0 ( 2683) P:80 I:10000 C:  10000 Min:      4 Act:   17 Avg:   44 Max:

   17692

policy: fifo: loadavg: 0.15 0.23 0.22 1/343 2690
----------------------------------------------------------------------

2.6.34.8-68.rt0.3.fc13.ccrma.i686.rtPAE

----------------------------------------------------------------------
while true ; do ./cyclictest -t1 -p 80 -n -i 10000 -l 10000 ; sleep 10; done

policy: fifo: loadavg: 0.19 0.30 0.13 1/355 2561
T: 0 ( 2542) P:80 I:10000 C:  10000 Min:      3 Act:   27 Avg:   33 Max:

     143

policy: fifo: loadavg: 0.03 0.20 0.11 1/354 2565
T: 0 ( 2564) P:80 I:10000 C:  10000 Min:      6 Act:   15 Avg:   55 Max:

     135

policy: fifo: loadavg: 0.53 0.27 0.14 3/401 2780
T: 0 ( 2568) P:80 I:10000 C:  10000 Min:      3 Act:    9 Avg:   21 Max:

     134

policy: fifo: loadavg: 0.50 0.39 0.20 1/405 2899
T: 0 ( 2869) P:80 I:10000 C:  10000 Min:      3 Act:   66 Avg:   36 Max:

     119

policy: fifo: loadavg: 0.13 0.28 0.18 1/404 2902
T: 0 ( 2902) P:80 I:10000 C:  10000 Min:      3 Act:   48 Avg:   31 Max:

     116

policy: fifo: loadavg: 0.10 0.27 0.17 1/405 2905
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