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SubjectLatency data - 2.6.14-rc3-rt13
Hi,
I'm still suffering the occasional xrun using Jack so I'm trying to
understand what information I can feed back on this. I turned on the
histogram feature for both IRQ-off and preempt-off. From what I can
see so far it seems that something is turning IRQs off for long
periods of time? I think that this is similar to what Lee Revell
showed the other day, but I don't know how to get the same sort of
printout he showed.

This is the Jack data:

nperiods = 2 for capture
nperiods = 2 for playback
08:16:26.401 Server configuration saved to "/home/mark/.jackdrc".
08:16:26.401 Statistics reset.
08:16:26.637 Client activated.
08:16:26.639 Audio connection change.
08:16:26.642 Audio connection graph change.
08:16:28.395 MIDI connection graph change.
08:16:28.472 MIDI connection change.
08:16:29.664 Audio connection graph change.
08:19:50.071 Audio connection graph change.
08:19:50.263 MIDI connection graph change.
08:19:50.273 MIDI connection graph change.
10:04:36.179 Audio connection graph change.
10:04:36.362 Audio connection change.
10:04:38.800 Audio connection graph change.
10:04:38.810 Audio connection graph change.
12:34:09.601 XRUN callback (1).
**** alsa_pcm: xrun of at least 0.133 msecs
13:09:41.344 MIDI connection graph change.
13:09:41.439 MIDI connection change.
13:09:42.427 Audio connection graph change.
13:09:45.919 Audio connection graph change.
13:09:45.941 Audio connection graph change.
13:09:45.960 MIDI connection graph change.

This is what I see for preempt off latency. This looks really good to me:

#Minimum latency: 0 microseconds.
#Average latency: 0 microseconds.
#Maximum latency: 1207040 microseconds.
#Total samples: 196871313
#There are 2 samples greater or equal than 10240 microseconds
#usecs samples
0 190504250
1 5881275
2 379533
3 69966
4 13858
5 5708
6 2287
7 7726
8 1771
9 465
10 649
11 935
12 948
13 720
14 573
15 329
16 139
17 71
18 46
19 27
20 21
21 7
22 3
23 2
24 1
25 0
26 0
27 0


However, for IRQ off latency I have far larger numbers. I Assume that
it's probably pretty bad that interrupts could be turned off for as
long as 4mS when I'm trying to run sub3mS?

#Minimum latency: 0 microseconds.
#Average latency: 4 microseconds.
#Maximum latency: 3998 microseconds.
#Total samples: 3102665680
#There are 0 samples greater or equal than 10240 microseconds
#usecs samples
0 3066905198
1 3817807
2 15630448
3 347330
4 55362
5 40098
6 27080
7 27740
8 22484
9 20298
10 15727
11 15346
12 14870
13 15258
14 101559
15 16152
<SNIP>
1365 18434
1366 15529
1367 12471
1368 11392
1369 13927
1370 21813
1371 39568
1372 87654
1373 250408
1374 535990
1375 577197
1376 370609
1377 120045
1378 20431
1379 5312
1380 5349
1381 8203
1382 14773
1383 15352
1384 9515
1385 5020
1386 3618
1387 3738
1388 5554
1389 8669
1390 8244
1391 6448
1392 4948
1393 4151
1394 5984
1395 10599
1396 19058
1397 41222
1398 109732
1399 360362
1400 354579
1401 113700
1402 11014
1403 1240
1404 754
1405 772
1406 963
1407 850
1408 445
1409 276
<SNIP>
3976 62
3977 57
3978 71
3979 70
3980 59
3981 61
3982 69
3983 76
3984 75
3985 72
3986 76
3987 80
3988 65
3989 64
3990 78
3991 70
3992 85
3993 128
3994 236
3995 358
3996 96
3997 0
3998 1
3999 0
4000 0
4001 0
4002 0


How can I get data that would be more useful in terms of real debug?

Thanks,
Mark
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