Re: O_DIRECT performance impact on 2.4.18 (was: Re: [PATCH] 2.5.14 IDE 56)

Lincoln Dale
2002-05-11T23:16:38Z

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.