From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pdx-out-010.esa.us-west-2.outbound.mail-perimeter.amazon.com (pdx-out-010.esa.us-west-2.outbound.mail-perimeter.amazon.com [52.12.53.23]) (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 7B0072D0607; Wed, 22 Oct 2025 03:41:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=52.12.53.23 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761104469; cv=none; b=jeeDtLblbM/aSJxFqFOunMDRyqnGFYHj14HaWKPZ97Pqu3Rd12J6jk639kHoq/UmsECUzwuUBkEqnPf/GqHUZI3vvJBVvJoGvn1sWYj7p96aD8We7gyuXLntmRtj7oqysB8qaEL/JW3gMIphkoDQXzivZYR5N9Um2VGIhEKltfk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761104469; c=relaxed/simple; bh=A4BYLRN069n/J1l2nN3miEA/LK2NvhnR3VjqVbVTln8=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=IJkqdjRdXl857rQPx7dCaYO/VOoBHxp16MvmdLZQ8aFi8QkCZaqco7WXZCgF726MqMlzmwYo3W0Wp0Y/MFOHqQBZ1wGmqudG3VBthmClwuTa6eaTUYsnGEUjjSUHL46hUo8iSdLSdHKyexYcGqCRXA8omBDZsjFjU6tbL4BfVnY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.co.jp; dkim=pass (2048-bit key) header.d=amazon.com header.i=@amazon.com header.b=s8DIafBU; arc=none smtp.client-ip=52.12.53.23 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.co.jp Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=amazon.com header.i=@amazon.com header.b="s8DIafBU" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazoncorp2; t=1761104465; x=1792640465; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=/BEU5aCOpTur4Q/ZQAqGm2S/L4I8jlo2kZlqzDsSpk8=; b=s8DIafBUZTRuVuTxkJS3Z8On760tsEqNqakme3d6z1q/2RvGE1+41Yzp khNz4m0uofXOKKBonYEmkordNneS8mhYjRTmcW+weT9YDw7NbCcuWMDVk m8L81fvBPfwv8fnl0NdzPMhJlNh539eG2ofto6GgcN3c8IJ3hWjMs+XMj bHKB3IJVilsSAdXknO8gCZ8ecVXxrHQF4A2Kr3J/RxxQ88DPsZdvAKmek 2zAWr70hLgFr9secGS3jgko647AOR/yfYdqOoer1363eGDFcfn/jS6/UM T6hMrWyOWskJaGuxB7SSs3nuunIy4a7cS5BzItP16Wz5A97PUCmGL8ZZD Q==; X-CSE-ConnectionGUID: 6PbBDKI2SA26RTx/HsoNAw== X-CSE-MsgGUID: SuArwaCtSfy62j3sCDdYIQ== X-IronPort-AV: E=Sophos;i="6.19,246,1754956800"; d="scan'208";a="5329617" Received: from ip-10-5-9-48.us-west-2.compute.internal (HELO smtpout.naws.us-west-2.prod.farcaster.email.amazon.dev) ([10.5.9.48]) by internal-pdx-out-010.esa.us-west-2.outbound.mail-perimeter.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Oct 2025 03:41:03 +0000 Received: from EX19MTAUWA001.ant.amazon.com [205.251.233.236:3455] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.42.150:2525] with esmtp (Farcaster) id 9bc5e0ec-1eec-40a5-8377-6626e9985264; Wed, 22 Oct 2025 03:41:03 +0000 (UTC) X-Farcaster-Flow-ID: 9bc5e0ec-1eec-40a5-8377-6626e9985264 Received: from EX19D001UWA001.ant.amazon.com (10.13.138.214) by EX19MTAUWA001.ant.amazon.com (10.250.64.217) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.20; Wed, 22 Oct 2025 03:41:02 +0000 Received: from b0be8375a521.amazon.com (10.37.244.10) by EX19D001UWA001.ant.amazon.com (10.13.138.214) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.20; Wed, 22 Oct 2025 03:40:59 +0000 From: Kohei Enju To: CC: , , , , , , , , , , , , , , , Subject: Re: [PATCH net-next v2 13/14] ixgbe: preserve RSS indirection table across admin down/up Date: Wed, 22 Oct 2025 12:40:45 +0900 Message-ID: <20251022034051.28052-2-enjuk@amazon.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20251021161006.47e42133@kernel.org> References: <20251021161006.47e42133@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: EX19D045UWC004.ant.amazon.com (10.13.139.203) To EX19D001UWA001.ant.amazon.com (10.13.138.214) On Tue, 21 Oct 2025 16:10:06 -0700, Jakub Kicinski wrote: >On Tue, 21 Oct 2025 12:59:34 +0900 Kohei Enju wrote: >> For example, consider a scenario where the queue count is 8 with user >> configuration containing values from 0 to 7. When queue count changes >> from 8 to 4 and we skip the reinitialization in this scenario, entries >> pointing to queues 4-7 become invalid. The same issue applies when the >> RETA table size changes. > >Core should reject this. See ethtool_check_max_channel() Indeed, you're right that the situation above will be rejected. I missed it. BTW, I think reinitializing the RETA table when queue count changes or RETA table size changes is reasonable for predictability and safety. Does this approach make sense to you? > >> Furthermore, IIUC, adding netif_is_rxfh_configured() to the current >> condition wouldn't provide additional benefit. When parameters remain >> unchanged, regardless of netif_is_rxfh_configured(), we already preserve >> the RETA entries which might be user-configured or default values, > >User may decide to "isolate" (take out of RSS) a lower queue, >to configure it for AF_XDP or other form of zero-copy. Install >explicit rules to direct traffic to that queue. If you reset >the RSS table random traffic will get stranded in the ZC queue >(== dropped). > You're correct about the ZC queue scenario. The original implementation (before this patch) would indeed cause this problem by unconditionally reinitializing. I believe this patch addresses that issue - it preserves the user configuration since neither queue count nor RETA table size changes in that case. If I'm misunderstanding your scenario, please let me know. I could update the logic to explicitly check netif_is_rxfh_configured() as in [1], though the actual behavior would be the same as [2] since the default RETA table is a deterministic function of (rss_indices, reta_entries): [1] Check user configuration explicitly: if (!netif_is_rxfh_configured(adapter->netdev) || adapter->last_rss_indices != rss_i || adapter->last_reta_entries != reta_entries) { // reinitialize } [2] Current patch: if (adapter->last_rss_indices != rss_i || adapter->last_reta_entries != reta_entries) { // reinitialize } Do you have any preference between these approaches, or would you recommend a different solution?