Re: [dm-devel] [PATCH 2/3] scsi_dh: Remove the workqueue usedforactivate

[Chandra Seetharaman <sekharan us ibm com>]

On Thu, 2009-05-07 at 22:09 -0500, Mike Christie wrote:
> Chandra Seetharaman wrote:
> > On Wed, 2009-05-06 at 22:32 -0500, Mike Christie wrote:
> >> Chandra Seetharaman wrote:
> >>> Since scsi_dh_activate() has become an asynchronous function,
> >>> we do not need a workqueue for submitting scsi_dh_activate().
> >>>
> >>> This patch just removes the workqueue that submits scsi_dh_activate().
> >>>
> >> Before this is merged, we need to convert the other device handlers to 
> >> use blk_execute_rq_nowait or use their own workqueue_struct right?
> > 
> > If we want those modules also behave async, then yes.
> > 
> > But, this set of 3 patches would work fine as I made the relevant
> > changes to those modules so that they work properly.
> >  
> 
> What was the point of the workqueue?
> 
> I think if you merged the patch and left the other modules as is you 
> would hit a problem where the multipathd work queue struct thread is 
> busy waiting on activate commands when it should be routing IO to paths 
> that do not need a activate.

I am sorry for not being clear. As I mentioned in my original posting, I
am working on making the other modules also async. WIll be posting those
patches in a day or two. May be I will resubmit this set (with your
suggestion for GFP_NOIO) along with those.

In my reply (above), I was just trying to say that these set of patches
work (with the caveat you noted).

> 
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