On Wed, Mar 28, 2018 at 05:48:24PM -0700, Jakub Kicinski wrote: > Hi! > > This set adds support for update and delete calls from the datapath, > as well as XADD instructions (32 and 64 bit) and pseudo random numbers. > The XADD support depends on verifier enforcing alignment which Daniel > recently added. XADD uses NFP's atomic engine which requires values > to be in big endian, therefore we need to keep track of which parts of > the values are used as atomics and byte swap them accordingly. Pseudo > random numbers are generated using NFP's HW pseudo random number > generator. > > Jiong tackles initial implementation of packet cache, which he describes > as follows: > > Memory reads on NFP would first fetch data from memory to transfer-in > registers, then move them from transfer-in to general registers. > > Given NFP is rich on transfer-in registers, they could serve as memory > cache. > > This patch tries to identify a sequence of packet data read (BPF_LDX) that > are executed sequentially, then the total access range of the sequence is > calculated and attached to each read instruction, the first instruction > in this sequence is marked with an cache init flag so the execution of > it would bring in the whole range of packet data for the sequence. > > All later packet reads in this sequence would fetch data from transfer-in > registers directly, no need to JIT NFP memory access. > > Function call, non-packet-data memory read, packet write and memcpy will > invalidate the cache and start a new cache range. > > Cache invalidation could be improved in the future, for example packet > write doesn't need to invalidate the cache if the the write destination > won't be read again.
Looks exciting. Applied to bpf-next, thank you Jakub.
