Re: [HACKERS] A Better External Sort?

On Wed, Oct 05, 2005 at 11:24:07AM -0400, Luke Lonergan wrote:
>Nope - it would be disk wait.

I said I/O overhead; i.e., it could be the overhead of calling the
kernel for I/O's. E.g., the following process is having I/O problems:

time dd if=/dev/sdc of=/dev/null bs=1 count=10000000
   
10000000+0 records in
   
10000000+0 records out
   
10000000 bytes transferred in 8.887845 seconds (1125132 bytes/sec)
   

   
real    0m8.889s
   
user    0m0.877s
   
sys     0m8.010s
   

it's not in disk wait state (in fact the whole read was cached) but it's
only getting 1MB/s.

Mike Stone