netdev - Re: [PATCH net-next 7/7] ibmvnic: Perform tx CSO during send scrq direct

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Message-ID: <2ee7dd51-c45a-494e-ae24-b47fa938d321@linux.ibm.com>
Date: Mon, 5 Aug 2024 08:52:57 -0500
From: Nick Child <nnac123@...ux.ibm.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: netdev@...r.kernel.org, bjking1@...ux.ibm.com, haren@...ux.ibm.com,
        ricklind@...ibm.com
Subject: Re: [PATCH net-next 7/7] ibmvnic: Perform tx CSO during send scrq
 direct



On 8/2/24 19:15, Jakub Kicinski wrote:
> On Thu,  1 Aug 2024 16:23:40 -0500 Nick Child wrote:
>> This extra
>> precaution (requesting header info when the backing device may not use
>> it) comes at the cost of performance (using direct vs indirect hcalls
>> has a 30% delta in small packet RR transaction rate).
> 
> What's "small" in this case? Non-GSO, or also less than MTU?

I suppose "non-GSO" is the proper term. If a packet is non-GSO
then we are able to use the direct hcall. On the other hand,
if a packet is GSO then indirect must be used, we do not have the option 
of direct vs indirect.