Re: O_DIRECT performance impact on 2.4.18 (was: Re: [PATCH]

[Lincoln Dale]

At 04:18 PM 11/05/2002 +0200, Roy Sigurd Karlsbakk wrote:
>Will the use of O_DIRECT affect disk elevatoring?

i believe the elevator is based on the 'block' layer and anything that goes 
thru it.  so the answer is that the requests would use the elevator.

for the test in question, i was doing sequential reads from the first block 
of each disk until some block later on in the disk.  (ie. a 2gbyte read or 
18gbyte read).
given that was the case and the only i/o ops were 'read' operations, 
elevator would make no difference here.

cheers,

lincoln.