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

Roy Sigurd Karlsbakk (roy@karlsbakk.net)
Sat, 11 May 2002 16:18:35 +0200

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On Friday 10 May 2002 17:55, Linus Torvalds wrote:
> On Fri, 10 May 2002, Lincoln Dale wrote:
> > so O_DIRECT in 2.4.18 still shows up as a 55% performance hit versus no
> > O_DIRECT. anyone have any clues?
>
> Yes.
>
> O_DIRECT isn't doing any read-ahead.
>
> For O_DIRECT to be a win, you need to make it asynchronous.

Will the use of O_DIRECT affect disk elevatoring?

Sorry if this is OT - I just need to know

Please cc: to me as I'm not on the list

roy
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