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Miller" , Jakub Kicinski , Paolo Abeni , Simon Horman , netdev@vger.kernel.org, eric.dumazet@gmail.com, Neal Cardwell Subject: Re: [PATCH net] net: add net.core.qdisc_max_burst Message-ID: References: <20260107104159.3669285-1-edumazet@google.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260107104159.3669285-1-edumazet@google.com> On Wed, Jan 07, 2026 at 10:41:59AM +0000, Eric Dumazet wrote: > In blamed commit, I added a check against the temporary queue > built in __dev_xmit_skb(). Idea was to drop packets early, > before any spinlock was acquired. > > if (unlikely(defer_count > READ_ONCE(q->limit))) { > kfree_skb_reason(skb, SKB_DROP_REASON_QDISC_DROP); > return NET_XMIT_DROP; > } > > It turned out that HTB Qdisc has a zero q->limit. > HTB limits packets on a per-class basis. > Some of our tests became flaky. Hm, if q->limit is the problem here, why not introduce a new Qdisc option for this? > > Add a new sysctl : net.core.qdisc_max_burst to control > how many packets can be stored in the temporary lockless queue. This becomes global instead of per-Qdisc. If this is intended, you might want to document it explicitly in the documentation. Regards, Cong