[LAU] 2.6.39.1 Xruns last longer!! (was: 2.6.39.1 threadirqs vs. the rest: some numbers)

Aurelien tyranorl at free.fr
Tue Aug 9 07:00:13 UTC 2011


Hi!

(hope the subject won't redirect this mail straight in your spam!)

I'm using 2.6.39 + thread irqs for several days/weeks, with FFADO
(Saffire PRO 40), on a moroless Debian system.

I'm really happy with it, it works fine, my DSP load is way lower than
before, and I don't have that Big Kernel Lock problem anymore, which is
cool.

But, when having an Xrun (which occurs very rarely, like once every 6 or
7 hours average), it last really long (I would say something like 2-5
seconds), and is thus highly hearable (sounds really stop, no unsync 
clics, but a total silence).

I wondered whether someone had an explanation about this, as I can't
find a reason for that.

See you.
Aurélien


On Mon, Jun 13, 2011 at 05:38:11PM -0700, Fernando Lopez-Lezcano wrote :
> 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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-- 
Aurélien


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