On 16-06-01 01:52 PM, Alexei Starovoitov wrote:
> On Wed, Jun 01, 2016 at 10:20:54PM +0200, Daniel Borkmann wrote:
>> On 06/01/2016 06:50 PM, Jakub Kicinski wrote:
>>> Add hardware cls_bpf offload on our smart NICs. Detect if
>>> capable firmware is loaded and use it to load the code JITed
>>> with just added translator onto programmable engines.
>>>
>>> Signed-off-by: Jakub Kicinski <jakub.kicin...@netronome.com>
>>> Reviewed-by: Dinan Gunawardena <dgunaward...@netronome.com>
>>> Reviewed-by: Simon Horman <simon.hor...@netronome.com>
>> [...]
>>> +static int
>>> +nfp_net_bpf_offload_prepare(struct nfp_net *nn,
>>> + struct tc_cls_bpf_offload *cls_bpf,
>>> + struct nfp_bpf_result *res,
>>> + void **code, dma_addr_t *dma_addr, u16 max_instr)
>>> +{
>>> + unsigned int code_sz = max_instr * sizeof(u64);
>>> + u16 start_off, tgt_out, tgt_abort;
>>> + const struct tc_action *a;
>>> + int err;
>>> +
>>> + if (tc_no_actions(cls_bpf->exts))
>>> + return -EINVAL;
>>> +
>>> + tc_for_each_action(a, cls_bpf->exts) {
>>> + if (!is_tcf_gact_shot(a))
>>> + return -EINVAL;
>>> + }
>>> +
>>> + if (cls_bpf->exts_integrated)
>>> + return -EINVAL;
>>
>> So cls_bpf has two working modes as mentioned: da (direct-action) and non-da.
>> Direct-action is I would say the most typical way to run cls_bpf as it allows
>> you to more naturally and efficiently code programs in the sense that
>> classification
>> and action is already combined in a single program, so there's no additional
>> overhead of a linear action chain required, and a single program can already
>> have multiple action code outcomes (TC_ACT_OK, TC_ACT_SHOT, ...), so that it
>> is
>> usually enough to run a single cls_bpf instance, for example, on sch_clsact
>> ingress or egress parent, nothing more than that to get the job done. I think
>> the cls_bpf->exts_integrated test could probably come first and if it's
>> false,
>> we'd need to walk the actions?
>
> I think it makes sense to offload da mode only. Doing tc_for_each_action
> walk like above is ok, but the number of bpf programs with only separate
> gact is diminishingly small and we don't recommend to use it anymore.
> That's the stuff we used when da wasn't available.
>
+1 I've been using da mode only as well.
