netdev - Re: [PATCH v6 net-next 1/2] net: Prevent RPS table overwrite for active flows

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Message-ID: <20250728090155.384b2b14@kernel.org>
Date: Mon, 28 Jul 2025 09:01:55 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Krishna Kumar <krikku@...il.com>
Cc: netdev@...r.kernel.org, davem@...emloft.net, edumazet@...gle.com,
 tom@...bertland.com, pabeni@...hat.com, horms@...nel.org, sdf@...ichev.me,
 kuniyu@...gle.com, ahmed.zaki@...el.com, aleksander.lobakin@...el.com,
 atenart@...nel.org, krishna.ku@...pkart.com
Subject: Re: [PATCH v6 net-next 1/2] net: Prevent RPS table overwrite for
 active flows

On Mon, 28 Jul 2025 07:43:25 +0530 Krishna Kumar wrote:
> > > +                             if (hash != READ_ONCE(tmp_rflow->hash) ||
> > > +                                 next_cpu == tmp_cpu) {
> > > +                                     /*
> > > +                                      * Don't unnecessarily reprogram if:
> > > +                                      * 1. This slot has an active different
> > > +                                      *    flow.
> > > +                                      * 2. This slot has the same flow (very
> > > +                                      *    likely but not guaranteed) and
> > > +                                      *    the rx-queue# did not change.
> > > +                                      */  
> 
> I took some time to figure out the different paths here as it was a
> new area for me, hence I put this comment. Shall I keep it as the
> condition is not very intuitive?

To me it just restates the condition, so not worth keeping the comment.
You could add the explanation of the logic with more justifications to
the commit message if you'd like? (perhaps you have it there already..)