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From: "Hunt, David" <david.hunt@intel.com>
Subject: Re: [PATCH 1/5] mempool: add external mempool manager
	support
Date: Thu, 4 Feb 2016 17:34:46 +0000
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To: Olivier MATZ <olivier.matz@6wind.com>, dev@dpdk.org
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On 04/02/2016 14:52, Olivier MATZ wrote:
> Hi David,

[snip]

Just a comment on one of your comments:

> Why not using a similar mechanism than what we have for PMDs?
>
>      void rte_eal_driver_register(struct rte_driver *driver)
>      {
>          TAILQ_INSERT_TAIL(&dev_driver_list, driver, next);
>      }
>
> To do that, you just need to add a TAILQ_ENTRY() in your
> rte_mempool_handler structure. This would avoid to duplicate the
> structure into a static array whose size is limited.
>
> Accessing to the callbacks would be easier:
>
>      return mp->mp_handler->put(mp->rt_pool, obj_table, n);

One of the iterations of the code did indeed use this mechanism, however 
I ran into problems with multiple processes using the same mempool. In 
that case, the 'mp_handler' element of the mempool in your return 
statement  is only valid for one of the processes. Hence the need for 
and index that's valid for all processes rather than a pointer that's 
valid for only one. And it's not easy to quickly index into an element 
in a queue, hence the array of 16 mempool_handler structs.

[snip]

Rgds,
Dave.