On 01/20/2017 07:23 AM, Jan Kara wrote: > On Wed 11-01-17 18:35:02, Steve Kenton wrote: >> I first noticed this with 4.10rc2+ while testing some changes I was >> making to the UDF driver but it's neither a new problem nor related to my >> changes. Below is a test run on a stock Ubuntu 14.04 system with kernel >> 3.19 and the results are the same. If I copy large video files to the DVD >> I can put 4+GiB on the disk, it syncs as expected and life is good. If I >> try to copy Linus' 2.7GiB repo to the DVD it is still going after running >> overnight and after killing the copy sync does not return for hours, >> which hangs a graceful reboot. I should note that while the sync has not >> completed the filesystem on the DVD seems usable for the light testing I >> did using df, ls, find etc and the verbose copy was still proceeding if >> slowly when I killed it. > > Yeah, I think the problem is that seeking just kills the DVD drive and UDF > driver in Linux is not very good in avoiding them. So writing to a UDF > filesystem on DVD media directly simply does not work very well. Also if > you copy a directory tree, there are lots of inplace updates of directories > happening so that may contribute to slowness as well. So all in all I don't > think this was ever something we were trying to make work reasonably since > people don't tend to use DVD like this... > > Honza > Granted it was a stress test, I was just surprised by the magnitude of the slow down. Probably worth pursuing - later. Steve Kenton -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
