netdev - Re: [PATCH v6 net-next 4/5] net: page_pool: make stats available just for global pools

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Date: Tue, 30 Jan 2024 16:11:04 +0100
From: Jesper Dangaard Brouer <hawk@...nel.org>
To: Lorenzo Bianconi <lorenzo.bianconi@...hat.com>,
 Yunsheng Lin <linyunsheng@...wei.com>
Cc: Lorenzo Bianconi <lorenzo@...nel.org>, netdev@...r.kernel.org,
 davem@...emloft.net, kuba@...nel.org, edumazet@...gle.com,
 pabeni@...hat.com, bpf@...r.kernel.org, toke@...hat.com,
 willemdebruijn.kernel@...il.com, jasowang@...hat.com, sdf@...gle.com,
 ilias.apalodimas@...aro.org
Subject: Re: [PATCH v6 net-next 4/5] net: page_pool: make stats available just
 for global pools



On 30/01/2024 14.52, Lorenzo Bianconi wrote:
>> On 2024/1/29 21:07, Lorenzo Bianconi wrote:
>>>> On 2024/1/28 22:20, Lorenzo Bianconi wrote:
>>>>> Move page_pool stats allocation in page_pool_create routine and get rid
>>>>> of it for percpu page_pools.
>>>>
>>>> Is there any reason why we do not need those kind stats for per cpu
>>>> page_pool?
>>>>
>>>
>>> IIRC discussing with Jakub, we decided to not support them since the pool is not
>>> associated to any net_device in this case.
>>
>> It seems what jakub suggested is to 'extend netlink to dump unbound page pools'?
> 
> I do not have a strong opinion about it (since we do not have any use-case for
> it at the moment).
> In the case we want to support stats for per-cpu page_pools, I think we should
> not create a per-cpu recycle_stats pointer and add a page_pool_recycle_stats field
> in page_pool struct since otherwise we will endup with ncpu^2 copies, right?
> Do we want to support it now?
> 
> @Jakub, Jesper: what do you guys think?
> 


I do see an need for being able to access page_pool stats for all 
page_pool's in the system.
And I do like Jakub's netlink based stats.

--Jesper
(p.s. I'm debugging some production issues with page_pool and broadcom 
bnxt_en driver).