linux-kernel - Re: [PATCH net-next] page_pool: add a test module for page

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Message-ID: <b438256d-a233-4708-9a82-e4f5f4b86a63@huawei.com>
Date: Tue, 10 Sep 2024 18:46:08 +0800
From: Yunsheng Lin <linyunsheng@...wei.com>
To: Mina Almasry <almasrymina@...gle.com>
CC: <hawk@...nel.org>, <ilias.apalodimas@...aro.org>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>, "David S. Miller"
	<davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski
	<kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Shuah Khan
	<shuah@...nel.org>, <linux-kselftest@...r.kernel.org>
Subject: Re: [PATCH net-next] page_pool: add a test module for page_pool

On 2024/9/10 1:28, Mina Almasry wrote:
> On Mon, Sep 9, 2024 at 2:25 AM Yunsheng Lin <linyunsheng@...wei.com> wrote:
>>
>> The testing is done by ensuring that the page allocated from
>> the page_pool instance is pushed into a ptr_ring instance in
>> a kthread/napi binded to a specified cpu, and a kthread/napi
>> binded to a specified cpu will pop the page from the ptr_ring
>> and free it back to the page_pool.
>>
>> Signed-off-by: Yunsheng Lin <linyunsheng@...wei.com>
> 
> It seems this test is has a correctness part and a performance part.
> For the performance test, Jesper has out of tree tests for the
> page_pool:
> https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/lib/bench_page_pool_simple.c
> 
> I have these rebased on top of net-next and use them to verify devmem
> & memory-provider performance:
> https://github.com/mina/linux/commit/07fd1c04591395d15d83c07298b4d37f6b56157f

Yes, I used that testing ko too when adding frag API support for
page_pool.

The main issue I remembered was that it only support x86:(

> 
> My preference here (for the performance part) is to upstream the
> out-of-tree tests that Jesper (and probably others) are using, rather
> than adding a new performance test that is not as battle-hardened.

I looked through the out-of-tree tests again, it seems we can take the
best of them.
For Jesper' ko:
It seems we can do prefill as something that pp_fill_ptr_ring() does
in bench_page_pool_simple.c to avoid the noise from the page allocator.


For the ko in this patch:
It uses NAPI instead of tasklet mimicking the NAPI context, support
PP_FLAG_DMA_MAP flag testing, and return '-EAGAIN' in module_init()
to use perf stat for collecting and calculating performance data.

Is there other testcase or better practicing that we can learn from
Jesper' out of tree ko?

> 
> --
> Thanks,
> Mina
>