On Sun, 2012-04-22 at 12:03 -0400, Brian J. Murrell wrote: > I've got an HVR-1600 in a fairly fast machine (P4 3GHz, two cores) on a > 3.2.0 kernel and seem to be getting lots of this sort of thing: > > Apr 19 20:09:10 pvr kernel: [34651.015170] cx18-0: Skipped encoder MPEG, MDL 63, 62 times - it must have dropped out of rotation > Apr 19 20:10:05 pvr kernel: [34705.375793] cx18-0: Skipped encoder IDX, MDL 415, 2 times - it must have dropped out of rotation > Apr 19 20:12:45 pvr kernel: [34865.535784] cx18-0: Skipped encoder IDX, MDL 426, 2 times - it must have dropped out of rotation > Apr 19 20:12:45 pvr kernel: [34865.609900] cx18-0: Skipped encoder IDX, MDL 430, 1 times - it must have dropped out of rotation > Apr 19 20:12:45 pvr kernel: [34865.684180] cx18-0: Could not find MDL 426 for stream encoder IDX > Apr 19 20:12:58 pvr kernel: [34878.912976] cx18-0: Could not find MDL 430 for stream encoder IDX > Apr 19 20:13:00 pvr kernel: [34880.850172] cx18-0: Skipped encoder MPEG, MDL 53, 62 times - it must have dropped out of rotation > Apr 19 20:15:25 pvr kernel: [35025.696747] cx18-0: Skipped encoder IDX, MDL 435, 2 times - it must have dropped out of rotation > Apr 19 20:15:25 pvr kernel: [35025.771765] cx18-0: Skipped encoder IDX, MDL 439, 1 times - it must have dropped out of rotation > Apr 19 20:15:25 pvr kernel: [35025.847732] cx18-0: Could not find MDL 435 for stream encoder IDX > Apr 19 20:15:25 pvr kernel: [35025.901315] cx18-0: Skipped TS, MDL 82, 16 times - it must have dropped out of rotation > Apr 19 20:15:32 pvr kernel: [35032.370364] cx18-0: Skipped encoder IDX, MDL 435, 2 times - it must have dropped out of rotation > Apr 19 20:15:38 pvr kernel: [35039.074592] cx18-0: Could not find MDL 439 for stream encoder IDX > Apr 19 20:15:40 pvr kernel: [35040.938552] cx18-0: Skipped encoder MPEG, MDL 29, 62 times - it must have dropped out of rotation > Apr 19 20:18:05 pvr kernel: [35185.859652] cx18-0: Skipped encoder IDX, MDL 445, 2 times - it must have dropped out of rotation > Apr 19 20:18:05 pvr kernel: [35185.933816] cx18-0: Skipped encoder IDX, MDL 449, 1 times - it must have dropped out of rotation > Apr 19 20:18:05 pvr kernel: [35186.008176] cx18-0: Could not find MDL 445 for stream encoder IDX > Apr 19 20:18:19 pvr kernel: [35199.237035] cx18-0: Could not find MDL 449 for stream encoder IDX > Apr 19 20:18:19 pvr kernel: [35199.289870] cx18-0: Could not find MDL 49 for stream encoder MPEG > Apr 19 20:18:25 pvr kernel: [35205.879310] cx18-0: Skipped encoder IDX, MDL 450, 2 times - it must have dropped out of rotation > Apr 19 20:23:26 pvr kernel: [35506.147134] cx18-0: Skipped encoder IDX, MDL 402, 2 times - it must have dropped out of rotation > Apr 19 20:24:19 pvr kernel: [35559.705155] cx18-0: Skipped encoder MPEG, MDL 16, 62 times - it must have dropped out of rotation > > IIRC I was told previously that it was due to interrupts not being > serviced quickly enough. Am I recalling correctly? Yes. > Could that really be a problem even with a dual core 3GHz P4? Yes. You are looking at the evidence in those log messages. If, in your system, IRQ service for device A under some circumstances has precendence over IRQ service for the CX23418 and hence holds off its service; and the irq handler in the driver for device A decides to perform some some long I/O operations with device A; then it doesn't matter how fast your CPU is. You may wish to use perf or ftrace, or some other tool/method of measuring kernel interrupt handling latency to find out what causes any delays from the CX23418 raising its IRQ line to cx18_irq_handler() being called by the kernel. I can tell you that I have optimized cx18_irq_handler(), and the functions it calls, to death. I simply cannot make it perform significantly better. The required PCI MMIO operations to the CX23418 dominate the time consumed in cx18_irq_handler(). [I await "Challenge accepted" from anyone. ;) ] > Also, are those messages related to the clearqam path or the > MPEG2 hardware encoder path? i.e. are those digital recording > messages or analog recording messages? MPEG: analog video encoder DMA buffers IDX: MPEG index data DMA buffers from the analog video encoder TS: DTV (ATSC or QAM) DMA buffers Every message above in your log, indicates your system "lost" a notifcation from the CX23418 as it was too slow to respond to the CX23418's interrupt. Hence your recording/viewing of said stream missed some data. Note, the IDX stream only matters if you have an application that calls the VIDIOC_G_ENC_INDEX ioctl() to collect I-Frame offsets in the MPEG stream. That is very rare, so I would not worry about lost IDX buffers. > Cheers, > b. Regards, Andy -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
