From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [net-next-2.6 PATCH 2/3] ixgbe: Set MSI-X vectors to NOBALANCING and set affinity Date: Wed, 21 Oct 2009 21:50:31 -0700 (PDT) Message-ID: <20091021.215031.57955781.davem@davemloft.net> References: <20091021022626.32449.73883.stgit@localhost.localdomain> <20091021022713.32449.54868.stgit@localhost.localdomain> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: gospo@redhat.com, netdev@vger.kernel.org, peter.p.waskiewicz.jr@intel.com To: jeffrey.t.kirsher@intel.com Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:60041 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751994AbZJVEuI (ORCPT ); Thu, 22 Oct 2009 00:50:08 -0400 In-Reply-To: <20091021022713.32449.54868.stgit@localhost.localdomain> Sender: netdev-owner@vger.kernel.org List-ID: From: Jeff Kirsher Date: Tue, 20 Oct 2009 19:27:14 -0700 > From: Peter P Waskiewicz Jr > > This patch will set each MSI-X vector to IRQF_NOBALANCING to > prevent autobalance of the interrupts, then applies a CPU > affinity. This will only be done when Flow Director is enabled, > which needs interrupts to be processed on the same CPUs where the > applications are running. > > Signed-off-by: Peter P Waskiewicz Jr > Signed-off-by: Jeff Kirsher Just explain to me why irqbalanced in userspace cannot take care of this issue. Second, even if we cannot use irqbalanced for some reason, the last thing I want to see is drivers directly fiddling with interrupt states and attributes. Every driver is going to do it every so slightly differently, and often will get it wrong. There is also no global policy or policy control available when drivers do this stuff directly. And that's how we end up with situations where every driver behaves differently which results in a terrible user experience.