Studdering Problem

[johnnybonzo]

I have an issue with my HTPC setup. My machine is a dedicated GB-PVR server that also runs a torrent client in the background. Other than that, the machine is not used for anything else. A problem appears when the torrent client is downloading. Randomly, whatever I'm watching (Live TV/DVDs/AVIs...) skips a couple of frames periodically. I don't think it's the CPU since it runs below 50%. Whenever I notice the studdering, the Hard Drive light is illuminated (leading me to believe that the torrent client is writing to the disk, causing the problem.) It that possible? What can I do to rectify it?

FYI, the disk is a Seagate 160GB PATA drive, 16MB cache.

[Koenie]

You can try to run the torrent client in a low priority threat. Start it from a batch file or command line with the "Start /low" option. Maybe bump up the priority of GBPVR by setting the highpriority switch in the config.xml file.

I am afraid however that this will only partially solve yr problem as in my experience disk intensive tasks claim the disk for a too long period causing GBPVR to run out of buffer (once it is writing to the disk it does not go out of the way although the priority is low - probably a Windows issue). If yr torrrent client buffers a relatively large amount of data in memory before writing to disk you might want to try another client which writes more regularly to disk.

[BerkA]

johnnybonzo,

In addition to Koenie's ideas, also check that Windows is using DMA and write caching with your HDD.

These settings are normally set up to be optimal as soon as you install the hardware, but I've seen two cases when they change:
- If Windows detects repeated bus errors on IDE/SATA, it backs off to a conservative transfer mode -- like PIO. If this is the case, you'll find errors in the event log indicating the bus errors. You'll also see unusually-high CPU utilization by the Windows Kernel corresponding to HDD acceses. You should verify your hardware as this is indication of a hardware problem. Some people see this if they use a 40-pin IDE cable for a high-speed DMA mode. Google "dma pio" to find out more about it.
- Some people confuse the USB HDD write caching settings with their internal HDD write caching. While trying to optimize a USB HDD for quick removal, they turn off write caching to the internal HDDs.


To verify these settings:
- Go to Control Panel -> System -> Hardware -> Device Manager
- Expand the "IDE ATA/ATAPI controllers" section
- Right-click on the HDD controller, Select properties.
- Select the "Primary Channel" or "Secondary Channel" or "Advanced settings" tab. (This may be different for everone)

- Go to Control Panel -> System -> Hardware -> Device Manager
- Expand the "Disk drives" section
- Right-click on the HDD, Select properties

Between these two places, you should be able to find transfer mode (DMA/PIO) and Write caching settings.

[7ore]

My studdering problems stopped after I installed Prio, which made it possible to set the priority for PVRx2 to High and then save that setting.

[johnnybonzo]

Thanks for the replies.

Indeed my drive is operating in DMA mode. I had previously set PVRX2 (via config.xml) to operate in a high priority mode. I actually tweaked settings in Azureus to force it to write data to the drive more often (and cache less) and it has solved the problem (from what I can tell).

After many, many months of work, I finally have my HTPC running as I want it. Now if I can only get a faster internet connection...