netdev - Re: [PATCH net-next] tcp: try to defer / return acked skbs to originating CPU

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Message-ID: <20260129150459.29419003@kernel.org>
Date: Thu, 29 Jan 2026 15:04:59 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: Eric Dumazet <edumazet@...gle.com>
Cc: kuniyu@...gle.com, ncardwell@...gle.com, netdev@...r.kernel.org,
 davem@...emloft.net, pabeni@...hat.com, andrew+netdev@...n.ch,
 horms@...nel.org
Subject: Re: [PATCH net-next] tcp: try to defer / return acked skbs to
 originating CPU

On Mon, 19 Jan 2026 09:04:35 -0800 Jakub Kicinski wrote:
> > > Not sure if there's much we can do about that.. Perhaps we should have
> > > a shrinker that flushes the defer queues? I chatted with Shakeel briefly
> > > and it sounded fairly straightforward.    
> > 
> > I was mostly concerned about latency spikes, I did some tests here and
> > this seems fine.  
> 
> Looks like selftests run into the zerocopy Tx latency issue.
> I'll drop this version from patchwork..

Delaying zero copy forever is a bit of an annoyance.
I believe the same thing can happen in net-next with UDP 
but I haven't tested to confirm.

I assume the attached patch is out of question since it came up before?

View attachment "0001-net-periodically-flush-the-defer-queues.patch" of type "text/x-patch" (9443 bytes)