From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:7145 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753882Ab3JHHbr (ORCPT ); Tue, 8 Oct 2013 03:31:47 -0400 Date: Tue, 8 Oct 2013 09:33:02 +0200 From: Alexander Gordeev To: Michael Ellerman Cc: linux-kernel@vger.kernel.org, Bjorn Helgaas , Ralf Baechle , Benjamin Herrenschmidt , Martin Schwidefsky , Ingo Molnar , Tejun Heo , Dan Williams , Andy King , Jon Mason , Matt Porter , linux-pci@vger.kernel.org, linux-mips@linux-mips.org, linuxppc-dev@lists.ozlabs.org, linux390@de.ibm.com, linux-s390@vger.kernel.org, x86@kernel.org, linux-ide@vger.kernel.org, iss_storagedev@hp.com, linux-nvme@lists.infradead.org, linux-rdma@vger.kernel.org, netdev@vger.kernel.org, e1000-devel@lists.sourceforge.net, linux-driver@qlogic.com, Solarflare linux maintainers , "VMware, Inc." , linux-scsi@vger.kernel.org Subject: Re: [PATCH RFC 00/77] Re-design MSI/MSI-X interrupts enablement pattern Message-ID: <20131008073301.GC10669@dhcp-26-207.brq.redhat.com> References: <20131008043330.GF31666@concordia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20131008043330.GF31666@concordia> Sender: linux-pci-owner@vger.kernel.org List-ID: On Tue, Oct 08, 2013 at 03:33:30PM +1100, Michael Ellerman wrote: > On Wed, Oct 02, 2013 at 12:29:04PM +0200, Alexander Gordeev wrote: > > This technique proved to be confusing and error-prone. Vast share > > of device drivers simply fail to follow the described guidelines. > > To clarify "Vast share of device drivers": > > - 58 drivers call pci_enable_msix() > - 24 try a single allocation and then fallback to MSI/LSI > - 19 use the loop style allocation as above > - 14 try an allocation, and if it fails retry once > - 1 incorrectly continues when pci_enable_msix() returns > 0 > > So 33 drivers (> 50%) successfully make use of the "confusing and > error-prone" return value. Ok, you caught me - 'vast share' is incorrect and is a subject to rewording. But out of 19/58 how many drivers tested fallbacks on the real hardware? IOW, which drivers are affected by the pSeries quota? > And yes, one is buggy, so obviously the interface is too complex. Thanks > drivers/ntb/ntb_hw.c vmxnet3 would be the best example. > cheers -- Regards, Alexander Gordeev agordeev@redhat.com