From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 2899F21CA0E for ; Mon, 17 Feb 2025 14:48:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739803717; cv=none; b=u2+0QLunlbWOruOfolgpxv5vRMOV5BQcU1fy5Nf1eebd3v7wC+Z2fC9oEdeeETqSQAL6XzPHMHM+wdxFPA421jukdQFIN5WEmYyVAOCO7ngiDy9pw5npD08UxraQSfTVRKyYAvp5pPMRQDDFIJXxY9tQOqWCSGfaUVFF7WFTj/Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739803717; c=relaxed/simple; bh=8dhjqi6RQt0qUvh026uE2aPh7osHZWJ3X8d5NYVkLm8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=VBQAotwWTfACMg4ocxsiBMThU5b135jXH1m3KBECgX8WKv3qj4RDrw9lgE2qCt/4CxVd+91av+taJjK+joMM2n993fKVe2Sm7+OFl/DTBYyumbMJYRPVZEwAEbsiQ0vofN0CIqdH+5px5CZMgrufOkJpB3ti1/SO/vnILN5WF/s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=Mx4kRtrY; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Mx4kRtrY" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1739803714; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Rc6qCN4ETICC8azLtjrKdOIt2/nf2AWh/k3ErXHTy00=; b=Mx4kRtrYwSqJrvpRZyFiPMQ9XQpXthslg+UYXDRvXKfPfmu7D5p3dUH8q7kkaePfFixSbx Hf7CN0zMOhS8AqTiiQkohFaAxpx4XJup4ciPULKovkek3mjsN9iVlH6kGepcOgvB3n8pzT 6jp7RVGEOMSEbN/bnfb+j0wIDELnFmI= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-147-mrWbPi0hNja-OIALSx04Uw-1; Mon, 17 Feb 2025 09:48:32 -0500 X-MC-Unique: mrWbPi0hNja-OIALSx04Uw-1 X-Mimecast-MFC-AGG-ID: mrWbPi0hNja-OIALSx04Uw_1739803711 Received: by mail-wm1-f72.google.com with SMTP id 5b1f17b1804b1-439385b08d1so40485655e9.1 for ; Mon, 17 Feb 2025 06:48:32 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1739803711; x=1740408511; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Rc6qCN4ETICC8azLtjrKdOIt2/nf2AWh/k3ErXHTy00=; b=U3+2Rty4mD/lHOb+/VkHwj09bFkHmVDphwx9BZcaGuIZuvOXi4eXtPEIX0VNVrJamu MaOPek+82EhKqR2VymUTsRU1YRYf91/cidPQ4yBjk7QWNUm05xmYtuYBM2cWq44Lwu6G r9QADhTkQYHYPa8RBIpOUmL1oUHZeaJCqh+/NmTZGhpIzbK7OPP9vpTUpbZVHqe17Xg9 iL2AhsQemrrkbj11BtuR/19qmB/pBcRWncJi5iZXAEfvCXFYoJ4jYmhly10DQOYhSI/p AyKoW0sJresKOuCZWWRnxCX87/Npk/K0B1uwt3Wgur+IDuJp8cdbc7+GaNNP4qOZEggA n5kg== X-Gm-Message-State: AOJu0YwH5z1vRWWUkxiUZ6AU6XWsKwPZrMKd7UNpgG7azxQbloR+vAAM z7NUGzU5xPnWXBsEy4w/zLCjoQ0jTqdK5B58bI6cephAxDETRSG5h2UBWx8B/FAbNr7FdLN9hWp Ecv1Nz5SPuoHBfVITYp7UpoR99xSio/04wSFcJn8obBicqwk7sXRSUw== X-Gm-Gg: ASbGnctfzViNm2gg0Lsx9YbXQ91w6EAAddwdYS1fSTqyHtejCOUj0CCPI5AhmyM3vuI 8diMc8M/JMFx6uHKV5g+CU4Uo9QqCCrQBFYWhQ/FnK3HMjSk2DBhuT+Au5rI5NKQ7Fd5k4qNhaB sufimP97n8GHDH04tQDO8fP7mgdXw0cpr6+78//NFznHkMYX67GURs4etnkuM+1U3kiLvgTbq0c LMSGYV+fjmmlMtCMFWWdMwAPddIpkjV+7aqaCzKyeIC0fTK3r1lgyscMBEaGJL+HvmkQY2bCCgo odZJBUwgKBtYlsn6mIoUwUlMRcTZvafQYto= X-Received: by 2002:a05:600c:1c24:b0:439:6304:e28a with SMTP id 5b1f17b1804b1-4396e5b56e7mr110357185e9.0.1739803711291; Mon, 17 Feb 2025 06:48:31 -0800 (PST) X-Google-Smtp-Source: AGHT+IE4dxgzvDp9rr1MXvaB9poBGfjXuDnm6JJThZOwkW5h8/2vTvlD/gGcLEba0dFztjL+/zHSAQ== X-Received: by 2002:a05:600c:1c24:b0:439:6304:e28a with SMTP id 5b1f17b1804b1-4396e5b56e7mr110356975e9.0.1739803710901; Mon, 17 Feb 2025 06:48:30 -0800 (PST) Received: from [192.168.88.253] (146-241-89-107.dyn.eolo.it. [146.241.89.107]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-439617da91asm126105915e9.2.2025.02.17.06.48.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 17 Feb 2025 06:48:30 -0800 (PST) Message-ID: <41482213-e600-4024-9ca7-a085ac50f2db@redhat.com> Date: Mon, 17 Feb 2025 15:48:29 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net] net: allow small head cache usage with large MAX_SKB_FRAGS values To: Eric Dumazet Cc: netdev@vger.kernel.org, "David S. Miller" , Jakub Kicinski , Simon Horman , Sabrina Dubroca References: <6bf54579233038bc0e76056c5ea459872ce362ab.1739375933.git.pabeni@redhat.com> Content-Language: en-US From: Paolo Abeni In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2/12/25 9:47 PM, Eric Dumazet wrote: > diff --git a/include/net/tcp.h b/include/net/tcp.h > index 5b2b04835688f65daa25ca208e29775326520e1e..a14ab14c14f1bd6275ab2d1d93bf230b6be14f49 > 100644 > --- a/include/net/tcp.h > +++ b/include/net/tcp.h > @@ -56,7 +56,11 @@ DECLARE_PER_CPU(u32, tcp_tw_isn); > > void tcp_time_wait(struct sock *sk, int state, int timeo); > > -#define MAX_TCP_HEADER L1_CACHE_ALIGN(128 + MAX_HEADER) > +#define MAX_TCP_HEADER L1_CACHE_ALIGN(64 + MAX_HEADER) I'm sorry for the latency following-up here, I really want to avoid another fiasco. If I read correctly, you see the warning on top of my patch because you have the above chunk in your local tree, am I correct? If so, would you be ok to split the change in a 'net' patch doing the minimal fix (basically the initially posted patch) and following-up on net-next to adjust MAX_TCP_HEADER and SKB_SMALL_HEAD_SIZE as you suggest? I have a vague fear some encap scenario may suffer from the reduced TCP headroom, I would refrain from pushing such change on stable, if possible. Thanks, Paolo