From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=194.13.80.246 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794052389; b=O5FdAQdcI/hupMnaYsAWu7S4B9VIKapW+GiOpqPibUD2110YzmS4RiChVeraBLteuqaM NHNrDBuHhzPTXEkYdREH+hdj3wvZXOq9yFa69g5HzxObyRLo+qL/HTqxrWhNkQ27IHbiZ yHSK3oHO6Fh66bpxn/12WjnfzQlqNScvU3MbION1Yd2JAoUFUhrMrMuBNc1tpwrETImlh p+6+BeEc5EzTqrchmJYJwexGQoYvtBvtPBGCkU9HKN44KtS9MvzZ8/4tB3jTfLdwv4axe 5P3YKtapzQQDv0cabnB0er6lRMDcLiwtvo5Z1X8Uj67nP2PXYr/dJ6o6AuRZcwVkOlw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794052389; h=DMARC-Filter:Received:DKIM-Signature:MIME-Version:Date:From:To:Cc: Subject:In-Reply-To:References:Message-ID:X-Sender:Content-Type: Content-Transfer-Encoding:X-Last-TLS-Session-Version; bh=tve596h8zkYZfLnnzqz1wxSl0S3pzuQnyT+uXalhoXg=; b=OFSBUNxT3KER0G/Lu+EKFUgTYkBAiDtx010V9IN/UEWnw+ofTsMywsUYZBFL/ffiH38K ErY4B530ltqpfh6S2vfESzwInsvAh1wBjJcRN5ogdyqkcx4VI2QkoJr4AFavApaE1FbxB HFr6Y5oADVXk9wyfvcDWZwEaOt9z0MEPZdy9JGxgv9teCXpZaRlRzNT1jwzT0W78KKtBX gKou1Ywmv/Qc0+EgfPLJQgaPmpJ1WWprR0bLXBwTuOVty1Rooe0rX+PnwyekF2bswPPx/ i7SYEvZJpaDisF31jzellAr76hnQf0UM+A7l8X39ko9C0C+oOOyVvx24lzOF8ziIk0w== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none header.from=tipi-net.de; spf=pass smtp.mailfrom=tipi-net.de; dkim=pass header.d=tipi-net.de header.i=@tipi-net.de header.a=rsa-sha256 header.s=dkim header.b=ZU9qi2ej; arc=none smtp.remote-ip=194.13.80.246 Received: from mail.tipi-net.de (mail.tipi-net.de [194.13.80.246]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BE439606A326; Sat, 7 Nov 2026 11:53:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org BE439606A326 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=tipi-net.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=tipi-net.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=tipi-net.de header.i=@tipi-net.de header.a=rsa-sha256 header.s=dkim header.b=ZU9qi2ej Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id C61EAA0034; Sat, 07 Nov 2026 12:53:04 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tipi-net.de; s=dkim; t=1794052386; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=tve596h8zkYZfLnnzqz1wxSl0S3pzuQnyT+uXalhoXg=; b=ZU9qi2ej3MRvknrlmOJX1qCqg+H9HV4Tz8CnPAUi+ywathWMeA2VW4JtBUu/vvP+1Pn8NL /KfiKF1LjlW72wXB4OUZqohf/PmvXitctdT+Q81OlpHT9Fbh0R1W5VGnK16CyT9c5XNsOO p3y1BB5SvFKaDWJu1TPQbdYUHhZbEP9E63PDqqyEj8H42oEMVMiYqGpcH+rn3aJvuCNvnz nDvx+p9jDoBTZSlxwsGRPjxO5/WMgfJVNDA2/nsBJSjlhlArzcNyLGcCr2TXnXBdZYXU+B O7RzNk2UwAto5RoHEk/sUrGY1zilztWmIFRB/t3YujkGxsNuCSHgw8o9wCUXxA== X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Date: Sat, 07 Nov 2026 12:53:04 +0100 From: Nicolai Buchwitz To: Florian Fainelli Cc: Doug Berger , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Justin Chen , Broadcom internal kernel review list , Nikolay Aleksandrov , Jason Xing , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net] net: bcmgenet: cap the Tx queue threshold at the ring size In-Reply-To: <1b33c10e-fa25-427a-92a6-d26669712f09@broadcom.com> References: <20261106-nb-genet-txq-thld-net-v1-1-53bbac647b71@tipi-net.de> <1b33c10e-fa25-427a-92a6-d26669712f09@broadcom.com> Message-ID: <6c0446dbe8e63a7c6a6120d4a1d6ad0a@tipi-net.de> X-Sender: nb@tipi-net.de Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit X-Last-TLS-Session-Version: TLSv1.3 Hi Florian On 7.11.2026 01:14, Florian Fainelli wrote: > [...] > Eventually we will have to decide what to do with those other queues :D Probably sooner than later. Sashiko claims that this patch does not fully fix hte CONFIG_MAX_SKB_FRAGS=31 case. The check in bcmgenet_xmit() if (ring->free_bds <= (nr_frags + 1)) wants 33 free descriptors for a 31 frag skb and those rings hold 32. Arguably the bug is way older than this patch and you need a non-default config to hit. So IMHO the options are: Either linearize in bcmgenet_xmit() when the frame does not fit, or we drop the queues as I proposed in June [1]? With XDP in mind the second one seems more attractive, as it needs its own 64 descriptor ring. With the current split the main queue would end up with 64 descriptors, against 192 if the queues are collapsed. [1] https://lore.kernel.org/netdev/20260612205915.3156127-1-nb@tipi-net.de/ Regards Nicolai