linux-kernel - Re: [PATCH net] vmxnet3: use gro callback when UPT is enabled

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Message-ID: <754F4F49-97C9-45D3-9B2F-C7DAE3FFC30E@vmware.com>
Date:   Fri, 17 Mar 2023 20:27:50 +0000
From:   Ronak Doshi <doshir@...are.com>
To:     Yunsheng Lin <linyunsheng@...wei.com>,
        Jakub Kicinski <kuba@...nel.org>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Pv-drivers <Pv-drivers@...are.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Guolin Yang <gyang@...are.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net] vmxnet3: use gro callback when UPT is enabled



> On 3/16/23, 7:37 PM, "Yunsheng Lin" <linyunsheng@...wei.com <mailto:linyunsheng@...wei.com>> wrote:
> > On 2023/3/17 4:34, Jakub Kicinski wrote:
> > On Thu, 16 Mar 2023 05:21:42 +0000 Ronak Doshi wrote:
> >> Below are some sample test numbers collected by our perf team.
> >> Test socket & msg size base using only gro
> >> 1VM 14vcpu UDP stream receive 256K 256 bytes (packets/sec) 217.01 Kps 187.98 Kps -13.37%
> >> 16VM 2vcpu TCP stream send Thpt 8K 256 bytes (Gbps) 18.00 Gbps 17.02 Gbps -5.44%
> >> 1VM 14vcpu ResponseTimeMean Receive (in micro secs) 163 us 170 us -4.29%
> >
> > A bit more than I suspected, thanks for the data.
>
> Maybe we do some investigation to find out why the performace lost is more than
> suspected first.
>

I don’t think holding this patch to investigate why it takes longer in GRO is worthwhile.
That is a separate issue. UPT patches are already upstreamed to Linux and cross-ported to
relevant distros for customers to use. We need to apply this patch to avoid the performance
degradation in UPT mode as LRO is not available on UPT device.

I don’t see a functional issue with this patch. In UPT as LRO is not available, it needs to use GRO.

Thanks, 
Ronak