From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-184.mta0.migadu.com (out-184.mta0.migadu.com [91.218.175.184]) (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 E8D4722D4D0 for ; Thu, 29 May 2025 16:35:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.184 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748536527; cv=none; b=LmHGlESmUxd6lcjnEkf7g8XCyQk84okm6IWonkhqiy2/xO4qPGtga1V24XeQXTwzLf1VYRssmarOgwxvpCnnZbq1oOez8YyGTSi55lmXlb7Tns1wsF/8sUCVExEeCz8oKmEmM+L/zIL/Gc8dkuY/M4vJlM1FmWNqgSfjKwRdX3k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748536527; c=relaxed/simple; bh=IviTiIj3WvUWqOSsZPOwBlyQH4Z1m5aUiktfXlInqyI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=LeeklxgUS1IiQAVqk6FXFQHWLs8Y8zVghINoum2CRVzBm3wV4JbJg913IxFBSl9JwxlRDbNwVx5f5/PiE5k3lXKRvJunCexgF/TM9AVVc3jK/+UJFRCMhZGGhLEhfFlRvvm98Ap+BRjiwi0IQCJeH4rr076shbbKCHvt7YXI5io= 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=hqLZDpOW; arc=none smtp.client-ip=91.218.175.184 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="hqLZDpOW" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1748536513; 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=wgchDy6+ENMwqS/G43COtFv0WHKtbEpVBzFuObLQORs=; b=hqLZDpOWSYQ2FckvbhD5AL4P/5BzRpqjbhLUkGbGbVjsd4GxGVI2nKradu011PJcE3efzT VQi7WkK/+LrbhVboZKk9NzMSWHnauDVyZz3HkGFKQD4Fy/xbTNNrc0TMuLvtbBjK8Yf/NP E9xhQ00BqTYAH6m9BUGtxaWj3Ih+YQA= Date: Thu, 29 May 2025 12:35:09 -0400 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH net-next] net: xilinx: axienet: Configure and report coalesce parameters in DMAengine flow To: Andrew Lunn Cc: "Gupta, Suraj" , "andrew+netdev@lunn.ch" , "davem@davemloft.net" , "edumazet@google.com" , "kuba@kernel.org" , "pabeni@redhat.com" , "vkoul@kernel.org" , "Simek, Michal" , "Pandey, Radhey Shyam" , "horms@kernel.org" , "netdev@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "git (AMD-Xilinx)" , "Katakam, Harini" References: <20250525102217.1181104-1-suraj.gupta2@amd.com> <679d6810-9e76-425c-9d4e-d4b372928cc3@linux.dev> <6c99b7f5-b529-4efd-a065-1e0ebf01468e@lunn.ch> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Sean Anderson In-Reply-To: <6c99b7f5-b529-4efd-a065-1e0ebf01468e@lunn.ch> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 5/29/25 12:29, Andrew Lunn wrote: >> Yeah, but the reason is that you are trading latency for throughput. >> There is only one queue, so when the interface is saturated you will not >> get good latency anyway (since latency-sensitive packets will get >> head-of-line blocked). But when activity is sparse you can good latency >> if there is no coalescing. So I think coalescing should only be used >> when there is a lot of traffic. Hence why I only adjusted the settings >> once I implemented DIM. I think you should be able to implement it by >> calling net_dim from axienet_dma_rx_cb, but it will not be as efficient >> without NAPI. >> >> Actually, if you are looking into improving performance, I think lack of >> NAPI is probably the biggest limitation with the dmaengine backend. > > It latency is the goal, especially for mixing high and low priority > traffic, having BQL implemented is also important. Does this driver > have that? > > Andrew Yes, see commit c900e49d58eb ("net: xilinx: axienet: Implement BQL"). --Sean