Re: [Xen-devel] [patch 0/6] xenblk: Add O_DIRECT and O_SYNC support.

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 4/11/08 02:50, "Joe Jin" <joe.jin@xxxxxxxxxx> wrote:

> Resend.

I never saw this patchset before!

> [patch 0/6] xenblk: Add O_DIRECT and O_SYNC support.
> 
> This patchset to add O_DIRECT and O_SYNC support to xenblk driver.
> 
> At present xenblk driver, a ring buffer have introduced in backend and
> frontend, the cache got better for io performance. But at some conditions,
> data need write date to disk as soon as possible, this ring buffer made
> data could not sync to disk immediately, even open file with O_DIRECT or
> O_SYNC flag. Obviously some potential risks at os for IO operation,
> so sync data to disk asap which the file open with O_DIRECT/O_SYNC
> is meaningful for xenblk driver.
> 
> Please review and welcome comment.

How is this better than waiting in the domU (blkfront) domain to collect the
required asynchronous responses? Scattering changes into Linux filesystems
is a dead end unless you can get the changes accepted upstream via lkml.

 -- Keir



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