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Subject: Re: [bpf-next V2 PATCH 10/15] xdp: rhashtable with allocator ID to
 pointer mapping
To: Jesper Dangaard Brouer <brouer@redhat.com>
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From: Jason Wang <jasowang@redhat.com>
Message-ID: <6950eb76-8e3d-60f2-6de1-005a4e4fd3f6@redhat.com>
Date: Tue, 20 Mar 2018 10:26:50 +0800
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On 2018年03月19日 17:48, Jesper Dangaard Brouer wrote:
> On Fri, 16 Mar 2018 16:45:30 +0800
> Jason Wang <jasowang@redhat.com> wrote:
>
>> On 2018年03月10日 00:07, Jesper Dangaard Brouer wrote:
>>> On Fri, 9 Mar 2018 21:07:36 +0800
>>> Jason Wang <jasowang@redhat.com> 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.
>>>>>>>
>>>>>>> Signed-off-by: Jesper Dangaard Brouer<brouer@redhat.com>
>>>>>> A stupid question is, can we manage to unify this ID with NAPI id?
>>>>> Sorry I don't understand the question?
>>>> I mean can we associate page poll pointer to napi_struct, record NAPI id
>>>> in xdp_mem_info and do lookup through NAPI id?
>>> No. The driver can unreg/reg a new XDP memory model,
>> Is there an actual use case for this?
> I believe this is the common use case.  When attaching an XDP/bpf prog,
> then the driver usually want to change the RX-ring memory model
> (different performance trade off).

Right, but a single driver should only have one XDP memory model. (Or 
you want to all drivers to use this generic allocator?)

> When detaching XDP, then driver
> want to change back to old memory model. During this process, I
> believe, the NAPI-ID remains the same (right?).

Yes, but we can change the allocator pointer in the NAPI struct in this 
case too.

Thanks

>
>>>    without reloading
>>> the NAPI and generate a new NAPI id.
>>>