Re: Performance of packet writing: Blocksize matters

Johannes Niess wrote:
> stingray ~ # dd if=/dev/zero of=/dev/pktcdvd/dvdrw bs=32768 count=25000
> 25000+0 records in
> 25000+0 records out
> 819200000 bytes (819 MB) copied, 86.3305 seconds, 9.5 MB/s
> 
> stingray ~ # dd if=/dev/zero of=/dev/pktcdvd/dvdrw bs=32769 count=25000
> 25000+0 records in
> 25000+0 records out
> 819225000 bytes (819 MB) copied, 1312.45 seconds, 624 kB/s

These two commands appear to be exactly the same, yet have different 
results.  Can you explain this?

Also make sure /dev/hdc is using the noop io scheduler.