Hi, Andy Polyakov: > It appears that your system "balances" somewhere at 8x. Or in other words > slightly less than 8x is what it can deliver to the unit.
My theory is slightly different. I would blame it on latency and not on throughput because Tomasz can write DVD-R or DVD+R with 8x and no obvious performance glitches. My idea is that the drive blocks on a WRITE10 from the SGIO driver for a very short while, when it misses the write position due to rotation frequency. Then it becomes ready to accept the next write, but SGIO does not react fast enough, so that again the write position is missed and again blocking occurs. This would give a decisive role to the very early speed performance switch from 6x to 8x. It would also explain why in the same LBA range nominal 6x works better than nominal 8x. One could try to verify that idea by making a small pause at about 2 GB, wait for everything to calm down, and then resume writing. In my theory, after the pause there would be full 8x throughput, because then latency would be less critical due to higher sector frequency at the outer rim of the media. The pause would be made to break the bad rythm of blocking and resuming the WRITE commands. > How come just growisofs? Probably the fact that growisofs > constrains itself to 32KB data transfers libburn once used 64 kB but a year ago i switched to 32 kB because 64 kB did not work well with the combination of SuSE 9.0, USB, CD and audio sectors. I had a similar report before from Eduard Bloch about kernel 2.6 and USB but at that time i had neither a USB drive nor a 2.6 kernel. ------------------ To Tomasz: One could revoke that 32k change for an experiment: Currently in libburn/os-linux.h : /* ts A70523 : >32k seems not good with kernel 2.4 USB drivers and audio #define BURN_OS_TRANSPORT_BUFFER_SIZE 65536 */ #define BURN_OS_TRANSPORT_BUFFER_SIZE 32768 Experiment proposal: #define BURN_OS_TRANSPORT_BUFFER_SIZE 65536 make install and then run the test with cdrskin again. Have a nice day :) Thomas -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]