netdev - Re: [PATCH net-next] udp: add drop count for packets in udp_prod

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Message-ID: <CA+KdSGOzzb=vMWh6UG-OFSQgEapS4Ckwf5K8hwYy8hz4N9RVMg@mail.gmail.com>
Date: Wed, 7 Jan 2026 12:57:32 +0330
From: Mahdi Faramarzpour <mahdifrmx@...il.com>
To: Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc: Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org, davem@...emloft.net, 
	dsahern@...nel.org, edumazet@...gle.com, pabeni@...hat.com, horms@...nel.org
Subject: Re: [PATCH net-next] udp: add drop count for packets in udp_prod_queue

On Tue, Jan 6, 2026 at 10:52 PM Willem de Bruijn
<willemdebruijn.kernel@...il.com> wrote:
>
> Mahdi Faramarzpour wrote:
> > On Tue, Jan 6, 2026 at 5:24 AM Jakub Kicinski <kuba@...nel.org> wrote:
> > >
> > > On Mon,  5 Jan 2026 15:17:32 +0330 Mahdi Faramarzpour wrote:
> > > > This commit adds SNMP drop count increment for the packets in
> > > > per NUMA queues which were introduced in commit b650bf0977d3
> > > > ("udp: remove busylock and add per NUMA queues").
>
> Can you give some rationale why the existing counters are insufficient
> and why you chose to change then number of counters you suggest
> between revisions of your patch?
>
The difference between revisions is due to me realizing that the only error the
udp_rmem_schedule returns is ENOBUFS, which is mapped to UDP_MIB_MEMERRORS
(refer to function __udp_queue_rcv_skb), and thus UDP_MIB_RCVBUFERRORS
need not increase.

> This code adds some cost to the hot path. The blamed commit added
> drop counters, most likely weighing the value of counters against
> their cost. I don't immediately see reason to revisit that.
>
AFAIU the drop_counter is per socket, while the counters added in this
patch correspond
to /proc/net/{snmp,snmp6} pseudofiles. This patch implements the todo
comment added in
the blamed commit.

> > >
> > > You must not submit more than one version of a patch within a 24h
> > > period.
> > Hi Jakub and sorry for the noise, didn't know that. Is there any way to check
> > my patch against all patchwork checks ,specially the AI-reviewer
> > before submitting it?
>
> See https://www.kernel.org/doc/html/latest/process/maintainer-netdev.html
>
thanks.