From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from vps0.lunn.ch (vps0.lunn.ch [156.67.10.101]) (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 E49FD22DF8E; Thu, 29 May 2025 16:29:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=156.67.10.101 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748536202; cv=none; b=UzCg8xDQ1K65bkq0MzKeGpgUXTtqpIfCbSg+/5Z8A2kZlnUYAMo8Di6eqQZ8xgUQp0FizyiL1Y4+bGqzlLieugpzLpVYIQ4TSeuRJ0pT1i7aVwV2qowyRSYHZE21qcjwCneHpzTRHcdKcUlWuyPrQFt3iOtZg/ei6UJ6axMaeUQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748536202; c=relaxed/simple; bh=cHC5WHbEaJiuhxsuxlzB9f6LP8cIKNXdNA6XZ3a5How=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=fInYbKeKq+WPsPcO/chSmf/xVp6QyQocC8Zz94H0RCrduUA28RcEJmaCBT5pLqX2vuqRLCxXAalSHq5ip2jU56w/S49/R0eqtpS7KuLASoZlqIUhQbQYsIkaf01r0e3yq26awDqr8gvSAO1zMEnZKNF3HgM8Qro2/h4ntTytNPo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lunn.ch; spf=pass smtp.mailfrom=lunn.ch; dkim=pass (1024-bit key) header.d=lunn.ch header.i=@lunn.ch header.b=aNADSTtT; arc=none smtp.client-ip=156.67.10.101 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lunn.ch Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lunn.ch Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=lunn.ch header.i=@lunn.ch header.b="aNADSTtT" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lunn.ch; s=20171124; h=In-Reply-To:Content-Disposition:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:From:Sender:Reply-To:Subject: Date:Message-ID:To:Cc:MIME-Version:Content-Type:Content-Transfer-Encoding: Content-ID:Content-Description:Content-Disposition:In-Reply-To:References; bh=2ROEfGs105IHaeH5xuCxgG1C8SsFk2j1G03w+ZOsJUg=; b=aNADSTtTgd5KKMFX4Rm0nf0gHl HzZWzw7JvPDyh9a18qfJZxA/TUZljPkO7xFQdYpTgj+hmSgqlctoifkmV3ngNW5RF4ELFPpRuTW8d IZMMlCgcvUcX4dzZGbjF5JKsD54f/Wz5TGgwK5aBDbdib3jANcJNiRNSxCA9tAyfpw0E=; Received: from andrew by vps0.lunn.ch with local (Exim 4.94.2) (envelope-from ) id 1uKg8W-00EHbS-FC; Thu, 29 May 2025 18:29:44 +0200 Date: Thu, 29 May 2025 18:29:44 +0200 From: Andrew Lunn To: Sean Anderson 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" Subject: Re: [PATCH net-next] net: xilinx: axienet: Configure and report coalesce parameters in DMAengine flow Message-ID: <6c99b7f5-b529-4efd-a065-1e0ebf01468e@lunn.ch> References: <20250525102217.1181104-1-suraj.gupta2@amd.com> <679d6810-9e76-425c-9d4e-d4b372928cc3@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: > 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