> 在 2015年12月8日，下午9:34，Ola Liljedahl <ola.liljed...@linaro.org> 写道： > > On 8 December 2015 at 12:42, Bill Fischofer <bill.fischo...@linaro.org > <mailto:bill.fischo...@linaro.org>> wrote: > This is an interesting topic. I'd like to discuss this a bit during today's > ODP public call. > > I think the issue is that while a ring is a very useful implementation > construct its semantics are very SW centric. > But isn't the use case here SW centric? > > Perhaps there's opportunity here for a new Queue type that would permit an > implementation to implement the queue API as a ring for additional > performance? > I think it is a bad idea to overload the ODP queue with another type of usage > and implied implementation. Better to define a new ODP object. > > What are the real requirements of the "ring" as used by the cuckoo hash > design? Enqueue/dequeue operations. Fixed size is OK? Storing arbitrary > objects (not just ODP events)?
The real requirement is use the ring as a sort of container. Fixed Size is OK. And the ring should be used to store any ODP events, since it is used as a container, like vector in C++ STL. > > > The scheduler itself could use this since its use of queues is subject to > the same issues. > > On Mon, Dec 7, 2015 at 11:39 PM, HePeng <xnhp0...@icloud.com > <mailto:xnhp0...@icloud.com>> wrote: > Hi Maxim, > I implement a new version of cuckoo hash based on the ODP buffer/pool. > > As I’ve mentioned earlier, the use of ring in cuckoo hash is like to > the use of > a container, e.g. a queue in C++ STL. In current ODP implementation, I found > that > the ODP queue is implemented more likely a facility for transmitting objects, > not > a container to store objects. Look at the ODP queue enqueue interface: > > int odp_queue_enq(odp_queue_t queue, odp_event_t ev); > > the *odp_event_t* is related to the events, but I only want to use odp_queue > to > storing and retrieving objects, any objects. > > > So I use ODP buffer/pool interfaces instead of ODP queue > for the new cuckoo hash implementation. > > However, compared to the previous implementation based on ring, this > version > suffers a serious performance degradation. The evaluation is carried out on a > Intel > servers. I test lookup time for 1000 lookups on a table storing 1 million > items. > The ODP buffer/pool version suffers at least a 2x performance degradation. > > This is the buffer/pool version, for 1M insert, and 1000 lookup time: > > Average insert time = 2.383836, lookup time = 0.000353, > > This is the ring version. > > Average insert time = 1.629115, lookup time = 0.000098 > > This performance degradation stems from the heavy implementation of > ODP buffer/pool. In the ring based one, all the key is stored in a big > array, and > the ring only stores the array indexes of each key. Keys are retrieved using > array indexes. > In the new one, I use ODP buffer to store the key content. Keys are retrieved > by > dereferencing a *odp_buffer_t* handle. > > With this high performance degradation, I suggest moving ring into > the odp/api > as a container implementation, and use the previous implementation of cuckoo > hash. > > > > > > > _______________________________________________ > lng-odp mailing list > lng-odp@lists.linaro.org <mailto:lng-odp@lists.linaro.org> > https://lists.linaro.org/mailman/listinfo/lng-odp > <https://lists.linaro.org/mailman/listinfo/lng-odp> > > > _______________________________________________ > lng-odp mailing list > lng-odp@lists.linaro.org <mailto:lng-odp@lists.linaro.org> > https://lists.linaro.org/mailman/listinfo/lng-odp > <https://lists.linaro.org/mailman/listinfo/lng-odp> > >
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