Re: [PATCH 2/3] pnfs: introduce pnfs private workqueue

[Benny Halevy <bhalevy@tonian.com>]

On 2011-09-21 14:42, Boaz Harrosh wrote:
> On 09/21/2011 02:27 PM, Benny Halevy wrote:
>>> Unless we do following:
>>> 1. preallocate memory for extent state convertion
>>> 2. use nfsiod/rpciod to handle bl_write_cleanup
>>> 3. for pnfs error case, create a kthread to recollapse and resend to MDS
>>> I don't quite understand. How do you use nfs state manager to do other tasks?
>>
>> You need to keep a list of things to do hanging off of the nfs client structure
>> and set a bit in cl_state telling the state manager it has work to do
>> and wake it up.  It then needs to go over the list of, say nfs_inodes
>> and call into the layout driver to handle the errors.
>>
>> Benny
> 
> Good god, Is it not already too complicated?
> 
> The LD is out of the picture. You all seemed to agree that
> the LD has reported an io_done on the nfsiod/rpciod, and in the error case
> Generic layer needs to do it's coalescing on some other thread. So
> your description above is not correct, the LD is out of the picture.
> 

True, if the ld cleanup on io_done is sufficient.

> It all looks too complicated for me. A pnfs workqueue for both 2 and 3
> above is very good. Specially since the workqueue also shares global
> pool threads, No? I like it that there is a preallocated thread for
> the error-case, think about it.

I'm fine too with using a workqueue for the error case.
But I'd rather have the common case done path do only lightweight,
wait free processing.

Benny

> 
> Thanks
> Boaz
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