netdev - Re: [PATCH V7 net-next 0/6] ethtool: add support to set/get tx copybreak buf size and rx buf len

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Message-ID: <4466b159-7476-f833-ec22-ee234b70110b@huawei.com>
Date:   Thu, 27 Oct 2022 08:49:48 +0800
From:   Yunsheng Lin <linyunsheng@...wei.com>
To:     Gal Pressman <gal@...dia.com>,
        Guangbin Huang <huangguangbin2@...wei.com>,
        <davem@...emloft.net>, <kuba@...nel.org>, <mkubecek@...e.cz>,
        <andrew@...n.ch>, <amitc@...lanox.com>, <idosch@...sch.org>,
        <danieller@...dia.com>, <jesse.brandeburg@...el.com>,
        <anthony.l.nguyen@...el.com>, <jdike@...toit.com>,
        <richard@....at>, <anton.ivanov@...bridgegreys.com>,
        <netanel@...zon.com>, <akiyano@...zon.com>, <gtzalik@...zon.com>,
        <saeedb@...zon.com>, <chris.snook@...il.com>,
        <ulli.kroll@...glemail.com>, <linus.walleij@...aro.org>,
        <jeroendb@...gle.com>, <csully@...gle.com>,
        <awogbemila@...gle.com>, <jdmason@...zu.us>,
        <rain.1986.08.12@...il.com>, <zyjzyj2000@...il.com>,
        <kys@...rosoft.com>, <haiyangz@...rosoft.com>, <mst@...hat.com>,
        <jasowang@...hat.com>, <doshir@...are.com>,
        <pv-drivers@...are.com>, <jwi@...ux.ibm.com>,
        <kgraul@...ux.ibm.com>, <hca@...ux.ibm.com>, <gor@...ux.ibm.com>,
        <johannes@...solutions.net>
CC:     <netdev@...r.kernel.org>, <lipeng321@...wei.com>,
        <chenhao288@...ilicon.com>, <linux-s390@...r.kernel.org>
Subject: Re: [PATCH V7 net-next 0/6] ethtool: add support to set/get tx
 copybreak buf size and rx buf len

On 2022/10/26 22:00, Gal Pressman wrote:
> On 18/11/2021 14:12, Guangbin Huang wrote:
>> From: Hao Chen <chenhao288@...ilicon.com>
>>
>> This series add support to set/get tx copybreak buf size and rx buf len via
>> ethtool and hns3 driver implements them.
>>
>> Tx copybreak buf size is used for tx copybreak feature which for small size
>> packet or frag. Use ethtool --get-tunable command to get it, and ethtool
>> --set-tunable command to set it, examples are as follow:
>>
>> 1. set tx spare buf size to 102400:
>> $ ethtool --set-tunable eth1 tx-buf-size 102400
>>
>> 2. get tx spare buf size:
>> $ ethtool --get-tunable eth1 tx-buf-size
>> tx-buf-size: 102400
> 
> Hi Guangbin,
> Can you please clarify the difference between TX copybreak and TX
> copybreak buf size?

Hi Gal,
'TX copybreak buf size' is the size of buffer allocated to a queue
in order to support copybreak handling when skb->len <= 'TX copybreak',

see hns3_can_use_tx_bounce() for 'TX copybreak' and
hns3_init_tx_spare_buffer() for 'TX copybreak buf size'.

> .
>