O_DIRECT as a mount option?

O_DIRECT as a mount option?

[Bob McElrath]

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With O_DIRECT (buffer cache bypass open() flag) now in the mainstream
kernel, I wonder if people would be opposed to making a "direct" mount
option, which would open all files on the filesystem with the O_DIRECT
flag, just as there exists a "sync" mount option to perform filesystem
transactions synchronously.

This would allow you to 
    mount -o direct,sync /dev/hdb1 /mnt/video
And would be useful for things like streaming video applications,
allowing the advantages of O_DIRECT without rewriting every application
you want to use.

Cheers,
-- Bob

Bob McElrath (rsmcelrath@students.wisc.edu) 
Univ. of Wisconsin at Madison, Department of Physics

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Re: O_DIRECT as a mount option?

[Andrea Arcangeli]

On Tue, Sep 25, 2001 at 12:51:44PM -0500, Bob McElrath wrote:
> With O_DIRECT (buffer cache bypass open() flag) now in the mainstream
> kernel, I wonder if people would be opposed to making a "direct" mount
> option, which would open all files on the filesystem with the O_DIRECT
> flag, just as there exists a "sync" mount option to perform filesystem
> transactions synchronously.
> 
> This would allow you to 
>     mount -o direct,sync /dev/hdb1 /mnt/video
> And would be useful for things like streaming video applications,
> allowing the advantages of O_DIRECT without rewriting every application
> you want to use.

you've to audit the app anyways since O_DIRECT enforces alignments on
buffer alignment and file offset.

Andrea