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 7DE3E2C11FE for ; Mon, 16 Feb 2026 17:49:38 +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=1771264178; cv=none; b=Tj3vDYotQlDvrQ/6xQM5sWHRJ6894IXgG84uKa+VQR8lT7Zku/St+GX8F8mbn2I87uP/5cmCrOnrHlgyI1etiiHxqRXAnFLseDMeWPA79hrId2RyqpnQZxLc0U216iBpwT52/3r3AVK1QaF781kzpda6OiXDiUby8dSp/9MwLZw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771264178; c=relaxed/simple; bh=gHSsLqqRaSL8TX3IJWyBQUV9R16r8UuifjrO/qmk0N4=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=i2udJxOYOAUHppCfAfHDxsQ8npQ9I431JG8R9N5IpbFtBWrEj8jU6woAlThupZvHqROKQ+OyL/XuYvVRnXcOyo9/bYaAjLhIjvBD1E0yEpUs2F1M06wBlEpU/GR7rGJ0/5O5H/PllwbYT/mtIDzn7Dht7Vu7cj57RxfTysJCZPE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=szHFvUXy; 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="szHFvUXy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A8228C116C6; Mon, 16 Feb 2026 17:49:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771264178; bh=gHSsLqqRaSL8TX3IJWyBQUV9R16r8UuifjrO/qmk0N4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=szHFvUXymL8hFN/Qey0wJXWgMsyu2nniFZqgwg8D9H5UiD/UgGD3TAf94Mx6eyRqW Y6QPb4Kxa7oVPP5qtfwASoVlnMb5B/k3gaHqDYb2Rl745TkMhMozAAxOlKyQSjR6/A me9ZL5bpEy14WmemctVFyFEtmZsoo2Xi9cJ57dchpF5r8aku7xhx0YV9nOWrLjLiaI DqnY54YRxRNmtrKi95fG82aLVySdytGe5dZ4/h8wp0FG0hwa1vO0AgUSQ54K3O3m3i 7MfShuI/8vH54OD26C/nA7BTPLTpWneEupscLMCkZywnQh/f6otpCauDgVaWDff8z0 JhCwt9Q+DBGdg== Date: Mon, 16 Feb 2026 09:49:36 -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: <20260216094936.5bf9d789@kernel.org> In-Reply-To: References: <20260117164255.785751-1-kuba@kernel.org> <20260117150346.72265ac3@kernel.org> <20260119090435.44b1da2d@kernel.org> <20260129150459.29419003@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 Mon, 16 Feb 2026 17:06:58 +0100 Eric Dumazet wrote: > > > Looks like selftests run into the zerocopy Tx latency issue. > > > I'll drop this version from patchwork.. > > > > Delaying zero copy forever is a bit of an annoyance. > > I believe the same thing can happen in net-next with UDP > > but I haven't tested to confirm. > > > > I assume the attached patch is out of question since it came up before? > > I think I totally missed your email :/ > > What about not attempting defer for zero copy skbs ? > > It turns out existing patch e20dfbad8aab ("net: fix napi_consume_skb() > with alien skbs") is already a problem for zcopy. We definitely need either this or the timer patch I attached, for UDP. I put the TCP write side on a back burner because slab sheaves got merged, I think skb defer free will still make a difference but IDK how much. Maybe juice will no longer be worth the squeeze?