Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 13 Jul 2023 09:57:47 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Yan Zhai <yan@cloudflare.com>
Cc:     Ivan Babrou <ivan@cloudflare.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, kernel-team@cloudflare.com,
        Eric Dumazet <edumazet@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        Paolo Abeni <pabeni@redhat.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        David Ahern <dsahern@kernel.org>
Subject: Re: [RFC PATCH net-next] tcp: add a tracepoint for
 tcp_listen_queue_drop
Message-ID: <20230713095747.580c2b0a@kernel.org>
In-Reply-To: <CAO3-PbqtdX+xioiQfOCxVovKVYUgXkrmsfw+1wTYoJiAq=2=ng@mail.gmail.com>
References: <20230711043453.64095-1-ivan@cloudflare.com>
        <20230711193612.22c9bc04@kernel.org>
        <CAO3-PbrZHn1syvhb3V57oeXigE_roiHCbzYz5Mi4wiymogTg2A@mail.gmail.com>
        <20230712104210.3b86b779@kernel.org>
        <CAO3-PbqtdX+xioiQfOCxVovKVYUgXkrmsfw+1wTYoJiAq=2=ng@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Wed, 12 Jul 2023 21:43:32 -0500 Yan Zhai wrote:
> Those are not unnecessary calls, e.g. a lot of those kfree_skb come
> from iptables drops, tcp validation, ttl expires, etc. On a moderately
> loaded server, it is called at a rate of ~10k/sec, which isn't
> terribly awful given that we absorb millions of attack packets at each
> data center. We used to have many consume skb noises at this trace
> point with older versions of kernels, but those have gone ever since
> the better separation between consume and drop.

I was hoping you can break them down by category.

Specifically what I'm wondering is whether we should also have 
a separation between policy / "firewall drops" and error / exception
drops. Within the skb drop reason codes, I mean.