netdev - Re: [EXT] Re: [PATCH net-next v2 3/4] octeon_ep: implement xmit

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Date: Thu, 26 Oct 2023 07:44:54 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Shinas Rasheed <srasheed@...vell.com>
Cc: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Haseeb Gani
 <hgani@...vell.com>, Vimlesh Kumar <vimleshk@...vell.com>,
 "egallen@...hat.com" <egallen@...hat.com>, "mschmidt@...hat.com"
 <mschmidt@...hat.com>, "pabeni@...hat.com" <pabeni@...hat.com>,
 "horms@...nel.org" <horms@...nel.org>, "davem@...emloft.net"
 <davem@...emloft.net>, "wizhao@...hat.com" <wizhao@...hat.com>,
 "konguyen@...hat.com" <konguyen@...hat.com>, Veerasenareddy Burru
 <vburru@...vell.com>, Sathesh B Edara <sedara@...vell.com>, Eric Dumazet
 <edumazet@...gle.com>
Subject: Re: [EXT] Re: [PATCH net-next v2 3/4] octeon_ep: implement
 xmit_more in transmit

On Thu, 26 Oct 2023 07:57:54 +0000 Shinas Rasheed wrote:
> >The recommended way of implementing 'driver flow control'  
> is to stop the queue once next packet may not fit, and then use
> netif_xmit_stopped() when deciding whether we need to flush or we can
> trust xmit_more. see 
> https://urldefense.proofpoint.com/v2/url?u=https-3A__www.kernel.org_doc_html_next_networking_driver.html-23transmit-2Dpath-2Dguidelines&d=DwICAg&c=nKjWec2b6R0mOyPaz7xtfQ&r=1OxLD4y-oxrlgQ1rjXgWtmLz1pnaDjD96sDq-cKUwK4&m=FyJHTb5Z2u9DTFSYPU38S5kPcP5KvwGWzY-DPcqOl1gdnm7ToZhTFpyvhLMqh1hd&s=dBMmwfWKAi0UH3nrz7j9kYnAodDjuN3LZ5tC2aL_Prs&e= 
> 
> >> In the skeleton code above, as I understand each tx desc holds a skb frag and hence there can be possibility of receiving a full-sized skb, stopping the queue but on receiving another normal skb we should observe our queue to be stopped. This doesn't arise in our case as even if the skb is full-sized, it will only use a single tx descriptor so we can be sure if queue has been stopped, the write index will only be updated once posted (and read) tx descriptors are processed in napi context and queues awoken.  
> 
> Please correct me if I'm wrong anywhere (sorry if so) to further my understanding, and again thanks for your time!

Could you please do some training on how to use normal / mailing list
style email at Marvell? Multiple people from Marvell can't quote
replies correctly, it makes it hard to have a conversation and help
y'all.