From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.tipi-net.de (mail.tipi-net.de [194.13.80.246]) (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 A51F0375ABE; Fri, 12 Jun 2026 21:00:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=194.13.80.246 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781298008; cv=none; b=atjfj/G7LwaByqJysKJlej89l+jbH6fbG94qmVpafRcFCw5gnC4Zy3cjN2orbzsTl2jBiCmaTcczUq9dC9rRftjH2i8iC6EDITPhVHrx9oEr7PK/yYvh2eF6GbTTPz1pn8AAehiah3/u1Yje423N3RWwQehUYZS9XbB2G9qRkvQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781298008; c=relaxed/simple; bh=KdHRTSDxsxSxKMGly9FdQAnP5B/pxArlmfPuJWSp5ro=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lZ+XkHsIkQXOJLc8xENMAadrcpqGA2IpnnuO5cBeqFUVjv6J/Z0twp1xtl7KJKS+drZPRULzIZhqfNOHgYvmzJVROmbaK9lOxLXREeo2Nyzlqtf9WUaZ8I7zfItSsMEBZypEKaSaf3S8Ys2goBikUfKCRvgONYOx24XWy+aDjkg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=tipi-net.de; spf=pass smtp.mailfrom=tipi-net.de; dkim=pass (2048-bit key) header.d=tipi-net.de header.i=@tipi-net.de header.b=0tzVjt0c; arc=none smtp.client-ip=194.13.80.246 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.b="0tzVjt0c" Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id F27BAA4F62; Fri, 12 Jun 2026 23:00:01 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tipi-net.de; s=dkim; t=1781298002; h=from:subject:date:message-id:to:cc:mime-version: content-transfer-encoding:in-reply-to:references; bh=QsLxA9Nj3hnIcCion65GXLKmwk+sracnvV53FIRar9A=; b=0tzVjt0cRH71qmClu2Hcc5521f6FhvSdqjvB2cTpIUnNwJL3wN/Jhe7HbBKYPbh8kJvc6y Ri+WJZrZBsp+Yu2jvbfHoNa9WiOzeERd2j2vidkOYXf0jjhjKkLbIC5qhuaBiy9AsAEWcE O8tH1E15K7WEPfGYAKwQmi9lPODWrW453m2cGMPgKv2XVcggIotUH8UhN/i2NUiY8Q3GYB r8o+W52Cv7tkl1Qdca8eKsEBQlVpQ5aw7quPy0TitZGbeUFwT+e17Cr39T+Mm7kIpPksLp odt2sHt1WqwBu4NRpYO52C6Un/e8TihHzhxkhTnuTENL8Jabbn7GfWk6S8DM2g== From: Nicolai Buchwitz To: Doug Berger , Florian Fainelli , bcm-kernel-feedback-list@broadcom.com, Andrew Lunn , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Justin Chen , Ovidiu Panait , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Nicolai Buchwitz Subject: [PATCH net-next 1/3] net: bcmgenet: collapse TX priority queues to a single queue Date: Fri, 12 Jun 2026 22:59:13 +0200 Message-ID: <20260612205915.3156127-2-nb@tipi-net.de> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260612205915.3156127-1-nb@tipi-net.de> References: <20260612205915.3156127-1-nb@tipi-net.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Last-TLS-Session-Version: TLSv1.3 The strict-priority TX queues can starve under multi-queue load and trip NETDEV_WATCHDOG. Justin's earlier series [1] worked around the symptom but kept the design. The multi-queue design was originally used for STB use cases that are no longer needed, as confirmed by Justin. v1 hw_params already exercises a single-queue path. Point v2-v4 at the same configuration: ring 0 takes the full BD pool, every per-ring loop collapses to one iteration, and netif_set_real_num_tx_queues drops to 1 via the existing tx_queues + 1 arithmetic. Tested on Raspberry Pi CM4 (BCM2711). The baseline kernel trips NETDEV_WATCHDOG within seconds under iperf3 UDP saturation (-u -b0 -P16 -t60). After the change the same test completes without a watchdog, and a single-stream 60 s UDP run sustains 956 Mbit/s with 0/4952890 datagrams lost. Single-stream TCP throughput is unchanged at 943 Mbit/s. [1] https://lore.kernel.org/netdev/20260406175756.134567-1-justin.chen@broadcom.com/ Signed-off-by: Nicolai Buchwitz --- drivers/net/ethernet/broadcom/genet/bcmgenet.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c b/drivers/net/ethernet/broadcom/genet/bcmgenet.c index ca403581357d..c892734b4cd0 100644 --- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c @@ -3751,8 +3751,8 @@ static const struct bcmgenet_hw_params bcmgenet_hw_params_v1 = { }; static const struct bcmgenet_hw_params bcmgenet_hw_params_v2 = { - .tx_queues = 4, - .tx_bds_per_q = 32, + .tx_queues = 0, + .tx_bds_per_q = 0, .rx_queues = 0, .rx_bds_per_q = 0, .bp_in_en_shift = 16, @@ -3769,8 +3769,8 @@ static const struct bcmgenet_hw_params bcmgenet_hw_params_v2 = { }; static const struct bcmgenet_hw_params bcmgenet_hw_params_v3 = { - .tx_queues = 4, - .tx_bds_per_q = 32, + .tx_queues = 0, + .tx_bds_per_q = 0, .rx_queues = 0, .rx_bds_per_q = 0, .bp_in_en_shift = 17, @@ -3787,8 +3787,8 @@ static const struct bcmgenet_hw_params bcmgenet_hw_params_v3 = { }; static const struct bcmgenet_hw_params bcmgenet_hw_params_v4 = { - .tx_queues = 4, - .tx_bds_per_q = 32, + .tx_queues = 0, + .tx_bds_per_q = 0, .rx_queues = 0, .rx_bds_per_q = 0, .bp_in_en_shift = 17, -- 2.53.0