This message is from the T13 list server.
On Wed, Jun 29 2005, Hale Landis wrote: > This message is from the T13 list server. > > > Jeff Garzik wrote: > >Going in the wrong direction. Talk to the people who write OS > >application software, because its they who generate the data access > >patterns. > > Lets be real - no one knows the actual physical data access patterns. > > Quiz: In a typical multitasking OS with ten applications running each > SEQUENTIALLY reading or writing files on the same disk drive - what is > the data access pattern actually seen by the drive? There's no answer to that, as the question doesn't make any sense - what is a 'typical multitasking OS'? What access pattern you will see depends on how clever the io scheduler is. On OS's still implementing the classical C-SCAN algorithm, you will see a crap access pattern for the case you list. For a more clever io scheduler, you will see largely interleaved sequential windows. -- Jens Axboe
