From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 19BE6281369 for ; Mon, 19 Jan 2026 17:04:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768842277; cv=none; b=OFXdO45VeOugmff+IH/2flZkyV8gyGBkbkap+S4wlHv8dUVTq4vv0v3in4fVE+vJnvm0RYFFHgSu5yRyiyvH0rNoVVgLTUpM7yRTAPjOfJ58yy9YWRzqvaV8ZcDLDc5dIFr16ZHj5zcLs/ZbmELpWI6P7b/vqx3Di7SRv7+WFqw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768842277; c=relaxed/simple; bh=Srr968woNABGoOESQcpP+dBa9pFWTSYiDZYxBonnKvc=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=FwPVUnP2Q6j8e+UhxNPGYSMlKx7ErpKji1WVdONI9gGI37stfnuk5eiyHiZwS2Pk/FBHb/Ofj6MwJJrqALL6SqsZZz9xFgUbn7b7w48Vy0O0+BXE7HP4L6AvrlPbqSJV1E+wrZr5C6TtyrAIbbgVx0PIRyWM6UeABngrl+iVVZo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WD2Gf0aV; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="WD2Gf0aV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90478C116C6; Mon, 19 Jan 2026 17:04:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768842276; bh=Srr968woNABGoOESQcpP+dBa9pFWTSYiDZYxBonnKvc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=WD2Gf0aV35Q/64BAvoGXfUDZcfLz6ph8ldUMxWYp0q1Cp5pIeCbOsLG7HTcZN6Ykc aaNaQGJFoM2AAkGzPdFzIttQ83xuP+/JnvrHG3ZaFmJ0RGdRuDiYdedJ1CyI/y3k1m Bom10uILutgw+8pBveX+iZfNIDtAScqa+dkyIozs9eA8/H6Hup641/4EJ/eDP2Bc1g 5zt4E/PUgNIQimCjUxv+lQWG4iRAmycK62sCQIidX8PAD/UrNciKc96WnGJQnCpimj iyoeQBxVlKMeGK9QKAC8PJaTiS1dSvzmj3fGv/je7Z3LSgIH9TN+WHSVg00wHNIJcz HeEnEf26g1J2w== Date: Mon, 19 Jan 2026 09:04:35 -0800 From: Jakub Kicinski To: Eric Dumazet Cc: kuniyu@google.com, ncardwell@google.com, netdev@vger.kernel.org, davem@davemloft.net, pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org Subject: Re: [PATCH net-next] tcp: try to defer / return acked skbs to originating CPU Message-ID: <20260119090435.44b1da2d@kernel.org> In-Reply-To: References: <20260117164255.785751-1-kuba@kernel.org> <20260117150346.72265ac3@kernel.org> 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-Transfer-Encoding: 7bit On Sun, 18 Jan 2026 13:15:00 +0100 Eric Dumazet wrote: > > > Also, if workers are away from softirq, they will only process the > > > defer queue in large patches, after receiving an trigger_rx_softirq() > > > IPI. > > > Any idea of skb_defer_free_flush() latency when dealing with batches > > > of ~64 big TSO packets ? > > > > Not sure if there's much we can do about that.. Perhaps we should have > > a shrinker that flushes the defer queues? I chatted with Shakeel briefly > > and it sounded fairly straightforward. > > I was mostly concerned about latency spikes, I did some tests here and > this seems fine. Looks like selftests run into the zerocopy Tx latency issue. I'll drop this version from patchwork.. > (I assume you asked Shakeel about the extra memory being held in the > per-cpu queue, and pcp implications ?) Under real load it helps quite a bit but real load flushes the queues frequently. I'll talk to him.