On 06/16/2016 09:47 AM, Hunt, David wrote: > > > On 15/6/2016 5:40 PM, Olivier MATZ wrote: >> >> >> On 06/15/2016 06:34 PM, Hunt, David wrote: >>> >>> >>> On 15/6/2016 1:03 PM, Olivier MATZ wrote: >>>> [...] >>>> >>>> The opaque pointer would be saved in mempool structure, and used >>>> when the mempool is populated (calling mempool_ops_alloc). >>>> The type of the structure pointed by the opaque has to be defined >>>> (and documented) into each mempool_ops manager. >>>> >>>> >>>> Olivier >>> >>> >>> OK, just to be sure before I post another patchset..... >>> >>> For the rte_mempool_struct: >>> struct rte_mempool_memhdr_list mem_list; /**< List of memory >>> chunks */ >>> + void *ops_args; /**< optional args for ops >>> alloc. */ >>> >>> (at the end of the struct, as it's just on the control path, not to >>> affect fast path) >> >> Hmm, I would put it just after pool_data. >> > > When I move it to just after pool data, the performance of the > mempool_perf_autotest drops by 2% on my machine for the local cache tests. > I think I should leave it where I suggested.
I don't really see what you call control path and data path here. For me, all the fields in mempool structure are not modified once the mempool is initialized. http://dpdk.org/browse/dpdk/tree/lib/librte_mempool/rte_mempool.h?id=ce94a51ff05c0a4b63177f8a314feb5d19992036#n201 So I don't think we should have more cache misses whether it's placed at the beginning or at the end. Maybe I'm missing something... I still believe it's better to group the 2 fields as they are tightly linked together. It could be at the end if you see better performance.