netdev - Re: [PATCH 1/2] net/mlx5: pre-initialize sprintf buffers

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Date: Tue, 20 Feb 2024 08:57:55 +0200
From: Yevgeny Kliteynik <kliteyn@...dia.com>
To: Zhu Yanjun <yanjun.zhu@...ux.dev>, Arnd Bergmann <arnd@...nel.org>,
 Saeed Mahameed <saeedm@...dia.com>, Leon Romanovsky <leon@...nel.org>
Cc: Arnd Bergmann <arnd@...db.de>, "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, Alex Vesker <valex@...dia.com>,
 Erez Shitrit <erezsh@...dia.com>, Hamdan Igbaria <hamdani@...dia.com>,
 netdev@...r.kernel.org, linux-rdma@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] net/mlx5: pre-initialize sprintf buffers

On 20-Feb-24 07:50, Zhu Yanjun wrote:
> External email: Use caution opening links or attachments
> 
> 
> 在 2024/2/19 18:04, Arnd Bergmann 写道:
>> From: Arnd Bergmann <arnd@...db.de>
>>
>> The debugfs files always in this driver all use an extra round-trip
>> through an snprintf() before getting put into a mlx5dr_dbg_dump_buff()
>> rather than the normal seq_printf().
>>
>> Zhu Yanjun noticed that the buffers are not initialized before being
>> filled or reused and requested them to always be zeroed as a
>> preparation for having more reused between the buffers.
> 
> I think that you are the first to find this.

The buffers are not initialized intentionally.
The content is overwritten from the buffer's beginning.
Initializing is not needed as it will only cause perf degradation.

-- YK