netdev - Re: [PATCH] net-sysfs: export gso_max

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Message-ID: <786ae327-f709-d09c-ceae-5f4789d537a1@gmail.com>
Date:   Fri, 24 Nov 2017 11:43:13 -0700
From:   David Ahern <dsahern@...il.com>
To:     Eric Dumazet <eric.dumazet@...il.com>,
        Solio Sarabia <solio.sarabia@...el.com>,
        netdev@...r.kernel.org, davem@...eloft.net,
        stephen@...workplumber.org
Cc:     kys@...rosoft.com, shiny.sebastian@...el.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net-sysfs: export gso_max_size attribute

On 11/24/17 11:32 AM, Eric Dumazet wrote:
> On Fri, 2017-11-24 at 10:14 -0700, David Ahern wrote:
>> On 11/22/17 5:30 PM, Solio Sarabia wrote:
>>> The netdevice gso_max_size is exposed to allow users fine-control
>>> on
>>> systems with multiple NICs with different GSO buffer sizes, and
>>> where
>>> the virtual devices like bridge and veth, need to be aware of the
>>> GSO
>>> size of the underlying devices.
>>>
>>> In a virtualized environment, setting the right GSO sizes for
>>> physical
>>> and virtual devices makes all TSO work to be on physical NIC,
>>> improving
>>> throughput and reducing CPU util. If virtual devices send buffers
>>> greater than what NIC supports, it forces host to do TSO for
>>> buffers
>>> exceeding the limit, increasing CPU utilization in host.
>>>
>>> Suggested-by: Shiny Sebastian <shiny.sebastian@...el.com>
>>> Signed-off-by: Solio Sarabia <solio.sarabia@...el.com>
>>> ---
>>
>> This should be added to rtnetlink rather than sysfs.
> 
> This is already exposed by rtnetlink [1]

It currently is read-only. This patch wants to control setting it.

> 
> Please lets not add yet another net-sysfs knob.

Which is my main point - no more sysfs files.