From: Jakub Kicinski <kuba@kernel.org>
To: Nick Child <nnac123@linux.ibm.com>
Cc: netdev@vger.kernel.org, bjking1@linux.ibm.com,
haren@linux.ibm.com, ricklind@us.ibm.com
Subject: Re: [PATCH net-next 7/7] ibmvnic: Perform tx CSO during send scrq direct
Date: Mon, 5 Aug 2024 12:09:59 -0700 [thread overview]
Message-ID: <20240805120959.70608deb@kernel.org> (raw)
In-Reply-To: <2ee7dd51-c45a-494e-ae24-b47fa938d321@linux.ibm.com>
On Mon, 5 Aug 2024 08:52:57 -0500 Nick Child wrote:
> 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.
It'd be great to add more exact analysis to the commit message.
Presumably the change is most likely to cause trouble in combination
with large non-GSO frames. Could you measure the perf impact when TSO
is disabled and MTU is 9k?
prev parent reply other threads:[~2024-08-05 19:10 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-01 21:23 [PATCH net-next 0/7] ibmvnic RR performance improvements Nick Child
2024-08-01 21:23 ` [PATCH net-next 1/7] ibmvnic: Only replenish rx pool when resources are getting low Nick Child
2024-08-01 21:23 ` [PATCH net-next 2/7] ibmvnic: Use header len helper functions on tx Nick Child
2024-08-01 21:23 ` [PATCH net-next 3/7] ibmvnic: Reduce memcpys in tx descriptor generation Nick Child
2024-08-01 21:23 ` [PATCH net-next 4/7] ibmvnic: Remove duplicate memory barriers in tx Nick Child
2024-08-01 21:23 ` [PATCH net-next 5/7] ibmvnic: Introduce send sub-crq direct Nick Child
2024-08-01 21:23 ` [PATCH net-next 6/7] ibmvnic: Only record tx completed bytes once per handler Nick Child
2024-08-01 21:23 ` [PATCH net-next 7/7] ibmvnic: Perform tx CSO during send scrq direct Nick Child
2024-08-03 0:15 ` Jakub Kicinski
2024-08-05 13:52 ` Nick Child
2024-08-05 19:09 ` Jakub Kicinski [this message]
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