Paul Ripke wrote:
> OK, what concerns me is those "random seeks/sec" rates. There's a huge
> difference there, and that could hurt other stats. It shouldn't be CPU
> bound (obviously), the only thing that comes to mind is in disk
> I/O scheduling - disksort. I wonder what the difference is.
> 
> [alternately, maybe I'm spending too much time looking at DBMS at work]


I would suspect the read ahead to be the culprit, since it reads in an
extra 128 KByte, when a random read (rounded up by file the file system
block size) ends at a 64KByte boundary. (see genfs_getpages())

Block-sized random reads on a filesystem with 8K blocks would read
an average of three blocks for every block requested. 


Stephan