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[24.6.151.244]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2fa0b9c5872sm4021465a91.0.2025.02.10.10.58.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Feb 2025 10:58:08 -0800 (PST) Date: Mon, 10 Feb 2025 10:58:06 -0800 From: Joe Damato To: Kurt Kanzenbach Cc: Tony Nguyen , Przemek Kitszel , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Sebastian Andrzej Siewior , intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org Message-ID: Mail-Followup-To: Joe Damato , Kurt Kanzenbach , Tony Nguyen , Przemek Kitszel , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Sebastian Andrzej Siewior , intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org References: <20250210-igb_irq-v1-0-bde078cdb9df@linutronix.de> <20250210-igb_irq-v1-3-bde078cdb9df@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250210-igb_irq-v1-3-bde078cdb9df@linutronix.de> X-Mailman-Original-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fastly.com; s=google; t=1739213889; x=1739818689; darn=lists.osuosl.org; h=in-reply-to:content-disposition:mime-version:references :mail-followup-to:message-id:subject:cc:to:from:date:from:to:cc :subject:date:message-id:reply-to; bh=4zHnrC6n0TeOwlGCGatrhmAfbiOBH4dMEPod+mMdLNo=; b=TkOmIllCG7cPUbU2Yq5thTQxivNg+t0XziQvBs4zPTDbAuUKb6QoRBoI72WPnxkZhm VmZXJO1tMvpXpGc3k/k7v570ZdiMX9baSo6P3fIatzexS2JhP7f5oru1a2klvSX8wdw7 XezJfQHypsN5tvGfgz/eY1WqWWlY5wxkceE/I= X-Mailman-Original-Authentication-Results: smtp2.osuosl.org; dmarc=pass (p=reject dis=none) header.from=fastly.com X-Mailman-Original-Authentication-Results: smtp2.osuosl.org; dkim=pass (1024-bit key, unprotected) header.d=fastly.com header.i=@fastly.com header.a=rsa-sha256 header.s=google header.b=TkOmIllC Subject: Re: [Intel-wired-lan] [PATCH 3/3] igb: Get rid of spurious interrupts X-BeenThere: intel-wired-lan@osuosl.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Intel Wired Ethernet Linux Kernel Driver Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-wired-lan-bounces@osuosl.org Sender: "Intel-wired-lan" On Mon, Feb 10, 2025 at 10:19:37AM +0100, Kurt Kanzenbach wrote: > When running the igc with XDP/ZC in busy polling mode with deferral of hard > interrupts, interrupts still happen from time to time. That is caused by > the igc task watchdog which triggers Rx interrupts periodically. > > That mechanism has been introduced to overcome skb/memory allocation > failures [1]. So the Rx clean functions stop processing the Rx ring in case > of such failure. The task watchdog triggers Rx interrupts periodically in > the hope that memory became available in the mean time. > > The current behavior is undesirable for real time applications, because the > driver induced Rx interrupts trigger also the softirq processing. However, > all real time packets should be processed by the application which uses the > busy polling method. > > Therefore, only trigger the Rx interrupts in case of real allocation > failures. Introduce a new flag for signaling that condition. > > Follow the same logic as in commit 8dcf2c212078 ("igc: Get rid of spurious > interrupts"). > > [1] - https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/?id=3be507547e6177e5c808544bd6a2efa2c7f1d436 > > Signed-off-by: Kurt Kanzenbach > --- > drivers/net/ethernet/intel/igb/igb.h | 3 ++- > drivers/net/ethernet/intel/igb/igb_main.c | 29 +++++++++++++++++++++++++---- > drivers/net/ethernet/intel/igb/igb_xsk.c | 1 + > 3 files changed, 28 insertions(+), 5 deletions(-) I am not an igb expert (nor do I have such a device), but after reading the source a bit this seems reasonable. I suppose perhaps a better direction in the future would be to convert the driver to the page pool, but in the meantime the proposed change seems reasonable. Reviewed-by: Joe Damato