On Mon, 2013-02-25 at 22:30 -0800, Neil Salstrom wrote: > Hello, > > I believe I have found a regression in drivers/net/loopback.c which was > introduced starting with the v3.7 kernel series (and also affects > v3.8). Oddly enough, it affects DVD playback (both physical disk and > .iso files) in MythTV (I'm using v0.26 and compile from source). I > don't know if MythTV mounts a .iso or DVD over a loopback device but for > whatever reason there is a problem. > > When playing a DVD there is a constant stuttering of the video and > corresponding audio dropouts. This is continual with mythfrontend logs > showing "Waiting for video buffers." > > I found that any kernel before v3.7 did not cause this issue so I did a > git bisect between v3.6 and v3.7. The resulting bisection was to commit > 0cf833a (net: loopback: set default mtu to 64K). > > I downloaded the source to v3.7.9 and reverted the line: > > dev->mtu = 64 * 1024; > > back to: > > dev->mtu = (16 * 1024) + 20 + 20 + 12; > > > The resulting kernel did not cause the playback stuttering. I have also > compiled v3.8.0 using (16 * 1024) + 20 + 20 + 12; and again had no problems. > > Please let me know if you have any questions. > > Thank you, > > Neil Salstrom >
Hmm, I suspect an application bug. Try to find what particular mtu value makes the application going bad, doing a dichotomy ? No need to recompile the kernel : ifconfig lo mtu XXXXX -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
