Hello Oliver, Oliver Hartkopp <socketcan@xxxxxxxxxxxx> writes: > Hello Rostislav, hello Eric, > > On 12.06.2012 16:50, Rostislav Lisovy wrote: > >> On Tue, 2012-06-12 at 16:33 +0200, Eric Dumazet wrote: >>> On Tue, 2012-06-12 at 16:03 +0200, Eric Dumazet wrote: >>>> On Tue, 2012-06-12 at 15:48 +0200, Rostislav Lisovy wrote: >>>>> em_canid is an ematch capable of classifying CAN frames according to >>>>> their CAN IDs. >>>>> >>>>> This RFC/Patch contains a reworked classifier initially posted in >>>>> http://www.spinics.net/lists/netdev/msg200114.html >>>>> The functionality is the same however there is almost 50% reduction >>>>> in the source code length. >>>>> >>>>> There is a slight difference between this ematch and other available >>>>> ematches. Other ematches implement only a simple match operation and >>>>> are meant to be combined with logic conjunctions (e.g. AND, OR). >>>>> Our ematch makes it possible to use up to 32 rules in single >>>>> 'configuration statement' (with OR semantics). This allows us to take >>>>> the advantage of the bit field data-structure in the implementation of >>>>> the match function. >>>>> >>>>> Example: canid(sff 0x123 eff 0x124 sff 0x230:0x7f0) >>>>> This ematch would match CAN SFF frames with the following IDs: >>>>> 0x123, 0x230--0x23f or EFF frame with ID 0x124. > > i tried to figure out the difference between the implementation as classifier > (link above) and this implementation as an ematch. > > Do we have any disadvantages using the ematch? The performance of ematch might be slightly lower than of standalone classifier. Rosta will compare the performance soon. > E.g. is it still possible to add additional ematches like checking for > patterns inside can_frame.data[] (which is located in skb->data) with > ematch_u32 or e.g. ematch_text ?? AFAIK, this should be possible and it will be a big advantage over implementation as a standalone classifier. Regards, -Michal -- To unsubscribe from this list: send the line "unsubscribe lartc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
