netdev - Re: [PATCH net-next 0/4] net: rps/rfs improvements

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Message-ID: <6984423.44csPzL39Z@eq59>
Date:   Wed, 29 Mar 2023 21:18:35 +0800
From:   Aiden Leong <aiden.leong@...sd.com>
To:     edumazet@...gle.com
Cc:     davem@...emloft.net, eric.dumazet@...il.com,
        kernelxing@...cent.com, kuba@...nel.org, netdev@...r.kernel.org,
        pabeni@...hat.com
Subject: Re: [PATCH net-next 0/4] net: rps/rfs improvements

On Wednesday, March 29, 2023 9:17:06 PM CST Aiden Leong wrote:
> Hi Eric,
> 
> I hope my email is not too off-topic but I have some confusion on how
> maintainers and should react to other people's work.
> 
> In short, you are stealing Jason's idea&&work by rewriting your
> implementation which not that ethical. Since your patch is based on his
> work, but you only sign-off it by your name, it's possible to raise lawsuit
> between Tencent and Linux community or Google.
> 
> I'm here to provoke a conflict because we know your name in this area and
> I'd to show my respect to you but I do have this kind of confusion in my
> mind and wish you could explain about it.
> 
Typo: I'm here NOT to provoke a conflict 
> There's another story you or Tom Herbert may be interested in: I was working
> on Foo Over UDP and have implemented the missing features in the previous
> company I worked for. The proposal to contribute to the upstream community
> was rejected later by our boss for unhappy events very similar to this one.
> 
> Aiden Leong
> 
> > Jason Xing attempted to optimize napi_schedule_rps() by avoiding
> > unneeded NET_RX_SOFTIRQ raises: [1], [2]
> > 
> > This is quite complex to implement properly. I chose to implement
> > the idea, and added a similar optimization in ____napi_schedule()
> > 
> > Overall, in an intensive RPC workload, with 32 TX/RX queues with RFS
> > I was able to observe a ~10% reduction of NET_RX_SOFTIRQ
> > invocations.
> > 
> > While this had no impact on throughput or cpu costs on this synthetic
> > benchmark, we know that firing NET_RX_SOFTIRQ from softirq handler
> > can force __do_softirq() to wakeup ksoftirqd when need_resched() is true.
> > This can have a latency impact on stressed hosts.
> > 
> > [1] https://lore.kernel.org/lkml/20230325152417.5403-1->
> 
> kerneljasonxing@...il.com/
> 
> > [2]
> > https://lore.kernel.org/netdev/20230328142112.12493-1-kerneljasonxing@gma
> > il.com/> 
> > Eric Dumazet (4):
> >   net: napi_schedule_rps() cleanup
> >   net: add softnet_data.in_net_rx_action
> >   net: optimize napi_schedule_rps()
> >   net: optimize ____napi_schedule() to avoid extra NET_RX_SOFTIRQ
> >  
> >  include/linux/netdevice.h |  1 +
> >  net/core/dev.c            | 46 ++++++++++++++++++++++++++++++---------
> >  2 files changed, 37 insertions(+), 10 deletions(-)


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