Linux-kernel mailing list archive 2000-23,: Re: FOPS needs Shutdown SIG Hook!!!

# Re: FOPS needs Shutdown SIG Hook!!!

Stephen C. Tweedie (sct@redhat.com)
Tue, 6 Jun 2000 21:21:17 +0100

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Hi,

On Mon, Jun 05, 2000 at 01:23:08PM +0100, Alan Cox wrote:
> > I am referring to the buffer cache on the disks. There will be a need to
> > flush/force write completion of data to the disk before power down if I
> > enable the intelligent write-caching in the hardware.
>
> If you do this then you won't be able to use IDE for journalling fs's. Before
> we can do cachable re-ordered writes on the device itself we have to
> implement store barrier points in the disk request queues so that the kernel
> can stop the drive re-ordering when it is not safe too

Ditto for any applications which rely on write ordering, such as
sendmail on a sync mail spool, or any database with log recovery.

Lying to the CPU about when the data is safe on disk is a bad thing
to do, in general.

--Stephen

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