From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-176.mta1.migadu.com (out-176.mta1.migadu.com [95.215.58.176]) (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 82A2F1E5724 for ; Wed, 8 Apr 2026 18:13:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.176 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775672007; cv=none; b=gh0bb2xGmZJHuvtmHywmavbqMasGF2ZAc1l0O4l4Nhf9Li3WrXGa6w5SMOBzWtzbly9oTYR06lTOA8r8lPE1nRGsXCWaBiABu/VF+wsH66NQrMsXsQGuSajPOpYtXbxV8FOzaunlP+QMKttGyDcfikTfUmq1veS6J71VVCrS6hg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775672007; c=relaxed/simple; bh=eERDK8MrgRVFpt8EPs6mScv+NPAcz47BRTMWRwRaxO8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ZkhsxnYpPwycDbShmS/RxaTktNEM/Jp8satPMB0VrdKq5pp1vaKHygVAjk3Nxc65EVkB6XFwQ7z9/7kdSRcXM2V8wToLdj10JPCafLS6WY2IwgKGrO3GQtjlytKZaIoylYQt7vRP5wTVcOZ+lyL0n3p7RjeyYTD8CUFXQXrTLeQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=fpqPtzxi; arc=none smtp.client-ip=95.215.58.176 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="fpqPtzxi" Date: Wed, 8 Apr 2026 11:12:22 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1775672003; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=yvj5h4HHK3avmY1kaN9kSeAcx7M966IB/bsppq/wjeY=; b=fpqPtzxiBAcO1LzeEqfVrmmPD1WZRWqf1D0cXahjB9nqdlirSLXRI2Ys4YaAnqzXLbr1Th 0h+Lzl0ZfAXzRyZDCXh4brASljnAAp1N0LGKGI61+84B+R3Q1hg+onnZ2O91Tz+baLn1UD XqGfeuybvA2UDxCObG5jwffCDo3sm8c= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Martin KaFai Lau To: Jason Xing , Willem de Bruijn Cc: Jakub Sitnicki , davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, willemb@google.com, martin.lau@kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, Jason Xing , Yushan Zhou Subject: Re: [PATCH net-next v2 3/4] bpf-timestamp: keep track of the skb when wait_for_space occurs Message-ID: <20264818422.Ya8u.martin.lau@linux.dev> References: <20260404150452.83904-1-kerneljasonxing@gmail.com> <20260404150452.83904-4-kerneljasonxing@gmail.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: X-Migadu-Flow: FLOW_OUT On Wed, Apr 08, 2026 at 11:15:09AM -0400, Willem de Bruijn wrote: > > Avoiding adding a new one makes the whole work extremely hard. I'm > > wondering since we have hwtstamp in shared info, why not add a > > software one for timestamping use? Then, we would support more > > different protocols in more different stages in a finer grain, which > > is a big coarse picture in my mind. > > I don't understand the need to store more data in the skb for BPF. Adding a field specific to bpf timestamping is not scalable. There will always be other bpf use cases that need to store something in a skb. There have been discussions about storing metadata for a skb which should solve the general bpf use cases. https://msgid.link/20260226-skb-local-storage-v1-0-4ca44f0dd9d1@cloudflare.com/ https://msgid.link/20260110-skb-meta-fixup-skb_metadata_set-calls-v1-0-1047878ed1b0@cloudflare.com/ > > With BPF hooks, the bpf program can record the relevant data directly > in a BPF map.