On Fri, 9 Mar 2018 16:08:58 +0800 Jason Wang <jasow...@redhat.com> wrote:
> On 2018年03月08日 21:08, Jesper Dangaard Brouer wrote: > > Use the IDA infrastructure for getting a cyclic increasing ID number, > > that is used for keeping track of each registered allocator per > > RX-queue xdp_rxq_info. Instead of using the IDR infrastructure, which > > uses a radix tree, use a dynamic rhashtable, for creating ID to > > pointer lookup table, because this is faster. > > > > The problem that is being solved here is that, the xdp_rxq_info > > pointer (stored in xdp_buff) cannot be used directly, as the > > guaranteed lifetime is too short. The info is needed on a > > (potentially) remote CPU during DMA-TX completion time . In an > > xdp_frame the xdp_mem_info is stored, when it got converted from an > > xdp_buff, which is sufficient for the simple page refcnt based recycle > > schemes. > > > > For more advanced allocators there is a need to store a pointer to the > > registered allocator. Thus, there is a need to guard the lifetime or > > validity of the allocator pointer, which is done through this > > rhashtable ID map to pointer. The removal and validity of of the > > allocator and helper struct xdp_mem_allocator is guarded by RCU. The > > allocator will be created by the driver, and registered with > > xdp_rxq_info_reg_mem_model(). > > > > It is up-to debate who is responsible for freeing the allocator > > pointer or invoking the allocator destructor function. In any case, > > this must happen via RCU freeing. > > > > Use the IDA infrastructure for getting a cyclic increasing ID number, > > that is used for keeping track of each registered allocator per > > RX-queue xdp_rxq_info. > > > > Signed-off-by: Jesper Dangaard Brouer<bro...@redhat.com> > > A stupid question is, can we manage to unify this ID with NAPI id? Sorry I don't understand the question? -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer
