netdev - Re: [PATCH net-next v4 0/4] Add support to do threaded napi busy poll

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Message-ID: <Z-Wbl6KoxKkbEemf@LQ3V64L9R2>
Date: Thu, 27 Mar 2025 11:40:23 -0700
From: Joe Damato <jdamato@...tly.com>
To: Stanislav Fomichev <stfomichev@...il.com>
Cc: Samiullah Khawaja <skhawaja@...gle.com>,
	Martin Karsten <mkarsten@...terloo.ca>,
	Jakub Kicinski <kuba@...nel.org>,
	"David S . Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
	almasrymina@...gle.com, willemb@...gle.com, netdev@...r.kernel.org
Subject: Re: [PATCH net-next v4 0/4] Add support to do threaded napi busy poll

On Wed, Mar 26, 2025 at 02:57:37PM -0700, Stanislav Fomichev wrote:
> On 03/26, Samiullah Khawaja wrote:
> > On Tue, Mar 25, 2025 at 10:47 AM Martin Karsten <mkarsten@...terloo.ca> wrote:
> > >
> > > On 2025-03-25 12:40, Samiullah Khawaja wrote:
> > > > On Sun, Mar 23, 2025 at 7:38 PM Martin Karsten <mkarsten@...terloo.ca> wrote:
> > > >>
> > > >> On 2025-03-20 22:15, Samiullah Khawaja wrote:

> > > > Nice catch. It seems a recent change broke the busy polling for AF_XDP
> > > > and there was a fix for the XDP_ZEROCOPY but the XDP_COPY remained
> > > > broken and seems in my experiments I didn't pick that up. During my
> > > > experimentation I confirmed that all experiment modes are invoking the
> > > > busypoll and not going through softirqs. I confirmed this through perf
> > > > traces. I sent out a fix for XDP_COPY busy polling here in the link
> > > > below. I will resent this for the net since the original commit has
> > > > already landed in 6.13.
> > > > https://lore.kernel.org/netdev/CAAywjhSEjaSgt7fCoiqJiMufGOi=oxa164_vTfk+3P43H60qwQ@mail.gmail.com/T/#t
> 
> In general, when sending the patches and numbers, try running everything
> against the latest net-next. Otherwise, it is very confusing to reason
> about..

I had mentioned in my previous review, but worth mentioning again...
using --base=auto when using format-patch to generate the base
commit SHA would be really useful to potentially help avoid this
problem.