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Thu, 21 May 2026 09:19:24 -0700 (PDT) Received: from [192.168.88.32] ([169.155.232.242]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49035ef2d93sm26744775e9.9.2026.05.21.09.19.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 21 May 2026 09:19:23 -0700 (PDT) Message-ID: Date: Thu, 21 May 2026 18:19:21 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v3] net: napi: Skip last poll when arming gro timer in busy poll To: Martin Karsten , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Simon Horman Cc: Joe Damato , Tariq Toukan , Gal Pressman , =?UTF-8?B?Qmrvv71ybiBU77+9cGVs?= , Frederik Deweerdt , Dragos Tatulea , netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260518181337.886459-1-mkarsten@uwaterloo.ca> <780d21ed-4ab3-478c-a932-6feb7aa6d7b4@redhat.com> From: Paolo Abeni Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/21/26 5:42 PM, Martin Karsten wrote: > On 2026-05-21 10:13, Paolo Abeni wrote: >> On 5/18/26 8:13 PM, Martin Karsten wrote: >>> + } else { >>> + /* All we really want here is to re-enable device interrupts. */ >>> + rc = napi->poll(napi, budget); >>> + /* We can't gro_normal_list() here, because napi->poll() might >>> + * have rearmed the napi (napi_complete_done()) in which case >>> + * it could already be running on another CPU. >>> + */ >>> + trace_napi_poll(napi, rc, budget); >>> + netpoll_poll_unlock(have_poll_lock); >>> + if (rc == budget) { >>> + gro_normal_list(&napi->gro); >> >> Not blocking, but I find the above slightly confusing after this >> refactor. Perhaps it should be re-worded? > > I'd be happy to reword, but I am not familiar with the internals of gro > processing, so would appreciate any help I can get? > > Should I try-and-error via subsequent patch submission(s) or can you > comment on this version: > > /* Use the driver poll to re-enable device interrupts. */ > rc = napi->poll(napi, budget); > trace_napi_poll(napi, rc, budget); > netpoll_poll_unlock(have_poll_lock); > if (rc == budget) { > /* If napi_complete_done has not been called by the > * driver poll, the napi needs to be rescheduled. > * Use the opportunity to pass up completed gro skbs. Possibly something alike the following: /* More work to do: no concurrent napi-related * irq is possible and the current thread can * pass up the pending skb batch. */ ?