Re: [PATCH 0/9] target: Add support for COMPARE_AND_WRITE (VAAI)emulation

[Douglas Gilbert]

On 13-08-20 05:53 PM, Nicholas A. Bellinger wrote:
> On Tue, 2013-08-20 at 23:29 +0200, Christoph Hellwig wrote:
> > On Tue, Aug 20, 2013 at 08:07:51PM +0000, Nicholas A. Bellinger wrote:
> > > It's also currently lacking the necessary sychronization between I/O
> > > submission of COMPARE_AND_WRITE verify instance and write instance
> > > user data, which is still being worked on in order to avoid additional
> > > overhead in the main I/O fast path.
> >
> > I don't think merging such a non-conforming implementation makes any sense.
>
> Yes, I don't intend to merge anything that's not fully functional.
>
> The idea was to get review going on these pieces first.  I'll be posting
> an PATCH-v2 to complete the implementation over the next days.
>
> > Also for a complex command like this with all it's race potential I would
> > really like to see some test cases to go along with it.
>
> Yes, Eric @ PureStorage has a sg_compare_write that I'm using to test
> this.  It's probably about time that this be included in upstream
> sg3-utils too..

Changelog for sg3_utils-1.35 [20130117] [svn: r476]
  - sg_compare_and_write: new utility
...

So it has been released for 6 months. Also version 1.36
has been released since then so you might check more
often. Does Eric's version have any improvements over the
version already in sg3_utils? [Apart from a shorter name ...]

Doug Gilbert


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