It may not have anyting to do with hardware or myth, and have everything to do with the kernel.
When I switched from 2.4.26 to 2.6.14, I ran into problems with stuttering. I had my kernel configured for 1000Hz and full pre-emption originally, and it would often get into a state where it would pause for about a second every few seconds. I switched the kernel to 250Hz and voluntary pre-emption and it seemed to help a little. Eventually, I realized that what was happening was that when it flushed it's dirty buffers to disk, playback would pause. What finally seemed to fix it was: # % of physical memory after which a process doing a write will be paused # untill dirty pages have been written # default 40 echo 50 > /proc/sys/vm/dirty_ratio # % of physical memory at which pdflush will be woken. Hopefull this will limit # system pauses for flushes # default 10 echo 5 > /proc/sys/vm/dirty_background_ratio I think that if you have too much memory, and an otherwise idle system, the disk flushes can get big enough to starve the frontend. Try re-compiling the kernel next time it starts stuttering. If the disk i/o it causes smooths out your playback, you know that's your problem. I was thinking of starting a new thread here on what people think the best config/tuning is on 2.6.14, since out of the box it's been a lot of trouble. Raphael Pooser <[EMAIL PROTECTED]> writes: > Chad wrote: > >>>>Well, there's some info missing here that might help ;) >>>> >>>>What CPU, videocard, soundcard and how are all these setup (if >>>>videocard is NVidia, what drivers, and are you using xvmc...). :) >>>> >>>>Also, on the Gentoo note, I use the SVN-ebuilds most the time (though >>>>occasionally I forget I have them and grab the latest SVN source and >>>>compile by hand :D ). >>>> >>>>Chad >>>>_______________________________________________ >>>>mythtv-users mailing list >>>>[email protected] >>>>http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users >>>> >>>> >>>> >>>> >>>> >>>What is xvmc? >>> >>> >> >>Xvideo Motion Compensation. In lamen terms it offloads the video to >>the graphics processing unit (GPU) from the CPU. It's drawback is >>that it generally only does mpeg2 decoding. >> >> >> >>>Is it really a good idea to use the trunk for something that's as >>>complete as mythtv? (I can understand using the trunk for something >>>pre-alpha.) >>> >>> >> >>Not always no. I think a lot of people on here suggest the Trunk >>because it's been a fair amount of time since the last stable release >>(which is a better guideline as to whether or not to use SVN/CVS or >>the official release). However, it's not absolutely necessary, it's >>just that there are some really good code updates/upgrades/additions >>in the SVN release that may make your system play nicer than the >>latest release (currently 0.18.x). >> >> >> >>>Here are the specs of the computers: >>> >>>The computer running mythbackend: >>>Asus K8N-E (nForce4 Ultra) >>>AMD Athlon 64 3700+ s939 >>>1GB PC3200 (2x512MB) >>>nVidia GeForce 6600 >>>Using onboard sound >>>Using onboard ethernet (forcedeth) >>>Gentoo i686 w/ linux-2.6.15-ck1 >>> >>> >> >>Sounds nice, also sounds like a TON of overkill in areas that don't >>need it if this is JUST a backend. :) >> >> >> >>>My Computer: >>>Asus K8V-X (Via K8T800) >>>AMD Athlon 64 3000+ s754 >>>1GB PC3200 >>>nVidia GeForce 6800GT 256MB >>>M-Audio Revolution 7.1 >>>Using onboard ethernet (marvel 88NE8001) >>>Gentoo i686 w/ linux 2.6.14-ck6 >>> >>> >> >>Certainly sounds like a decent enough system, as long you look into >>and use XvMC, you should be able to playback mpeg2 content without >>'stutter'. >> >> >> >>>Switch: Dlink DGS-1005D (both connected with Cat5e, speed is around >>>250-280Mb/s) >>>_______________________________________________ >>> >>> >> >>Good Luck! >> >>Chad >>_______________________________________________ >>mythtv-users mailing list >>[email protected] >>http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users >> >> >> > Reuben, > Just to second most of what Chad said, except the part about updating > your mythtv version. There are some nice updates to the code, but most > likely the stuttering has nothing to do with what version of myth you're > using, and everything to do with your graphics card drivers. Check your > processor usage (typing "top" at the command line or however you want to > do it) and most likely you'll see that you're near 100% usage on your > processor while playing back video. It'd be easiest to ssh into the > machine to check it while video is running, because if you do it on the > machine itself the usage will go down everytime you switch out fo the > video. Anyway, the processor utilization depends on resolution in the > case that you're not using xv or xvmc, and probably you're trying to > watch 640x480 or higher resolution files. Just make sure your graphics > card drivers are installed correctly (make sure the module's loading and > that X doesn't give you a message like "incorrect kernel module, no 3d > acceleration is available." Then make sure the option to enable xvmc is > enabled in xorg.conf. or xf86config-4. > I had the same problem with an ATI card and xv, and had the exact same > type of stuttering as you. Once I got xv working there was a night and > day difference. > I would say try and get xvmc working first, then worry about upgrading myth. > Raphael > _______________________________________________ > mythtv-users mailing list > [email protected] > http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users _______________________________________________ mythtv-users mailing list [email protected] http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
