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SubjectRe: [PATCH] barrier patch set
Chris Mason wrote:
> On Wed, 2004-03-31 at 09:08, Stephen C. Tweedie wrote:
>
>>Hi,
>>
>>On Tue, 2004-03-30 at 23:21, Jeff Garzik wrote:
>>
>>
>>>For IDE, O_DIRECT and O_SYNC can use special "FUA" commands, which don't
>>>return until the data is on the platter.
>>
>>fsync() is still really nasty, because that can require that we wait on
>>IO that was submitted by the VM before we knew that there was a
>>synchronous IO wait coming.
>
>
> Yes, it gets ugly in a hurry. Jeff, look at the whole thread about the
> O_DIRECT read vs buffered write races. I don't think we can use FUA for

Yes, I'm aware of the thread...


> fsync or O_SYNC without using it for every write.

Why not for O_SYNC? Is some crazy userspace application flipping this
bit on and off rapidly?


> We might be able to get away with using it on O_DIRECT.

Nod.

Jeff



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