On Saturday 20 July 2002 10:39 pm, Peter Osterlund wrote:
On Sat, 20 Jul 2002, Chris Clayton wrote:
I too have applied Ben's patches and the time taken to write the kernel sources to a CDRW on a 32x12x40 burner has reduced dramatically (from > 50 minutes to < 5). Good work.
But something else appears to have happened as well. For a week or two (and, I freely admit, without really knowing what i am looking for), I have been digging around seeing if I could find what might be causing the file corruption (2048 bytes of 0's) when large numbers of files (like the kernel sources) are written to a packet-formatted CDRW ). Having applied Ben's patches, that problem seems to have gone away too!
I think this is just a happy coincidence. I guess there exists a particular sequence of read/write commands that makes the packet driver confused if the timing is exactly right, and Ben's udf optimization just makes that much less likely to happen.
Remember that I saw this corruption also when using the ext2 filesystem. Anyway, investigating this corruption problem is on my todo list.
Did you always see only 0's in the corrupted data? I remember I saw pieces from other files and seemingly random data.
I've since done several more runs of the tests I outlined a few days ago. I have now experienced all the problems Peter has mentioned, corruptions on an ext2 filesystem created on a CDRW, pieces of other files embedded in the "target" file, and corruption in the middle of files with good data before and after. But to get these symptoms on ext2 I had to vary the test a bit. I copied the linux sources to the CDRW and diff'd them and they were OK (i.e. no corruption). But this time, instead of blanking the disk, I just copied the sources over the top of the first copy and this time I got 48 corrupted files - a new, all-time personal best for me :) All of the above is with a kernel without Ben's UDF patch.