From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Ellerman Subject: Re: [PATCH RFC 00/77] Re-design MSI/MSI-X interrupts enablement pattern Date: Wed, 9 Oct 2013 12:34:37 +1100 Message-ID: <20131009013437.GC23780@concordia> References: <20131008043330.GF31666@concordia> <20131008073301.GC10669@dhcp-26-207.brq.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from ozlabs.org ([203.10.76.45]:47788 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755962Ab3JIBek (ORCPT ); Tue, 8 Oct 2013 21:34:40 -0400 Content-Disposition: inline In-Reply-To: <20131008073301.GC10669@dhcp-26-207.brq.redhat.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Alexander Gordeev 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.or On Tue, Oct 08, 2013 at 09:33:02AM +0200, Alexander Gordeev wrote: > 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? It's not 19/58, it's 33/58. As to how many we care about on powerpc I can't say, so you have a point there. But I still think the interface is not actually that terrible. cheers From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Wed, 09 Oct 2013 03:34:48 +0200 (CEST) Received: from ozlabs.org ([203.10.76.45]:40860 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S6868703Ab3JIBepyiHxG (ORCPT ); Wed, 9 Oct 2013 03:34:45 +0200 Received: from concordia (ibmaus65.lnk.telstra.net [165.228.126.9]) (using TLSv1.2 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPSA id 0A1412C0099; Wed, 9 Oct 2013 12:34:39 +1100 (EST) Date: Wed, 9 Oct 2013 12:34:37 +1100 From: Michael Ellerman To: Alexander Gordeev 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: <20131009013437.GC23780@concordia> References: <20131008043330.GF31666@concordia> <20131008073301.GC10669@dhcp-26-207.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131008073301.GC10669@dhcp-26-207.brq.redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 38276 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: michael@ellerman.id.au Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips On Tue, Oct 08, 2013 at 09:33:02AM +0200, Alexander Gordeev wrote: > 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? It's not 19/58, it's 33/58. As to how many we care about on powerpc I can't say, so you have a point there. But I still think the interface is not actually that terrible. cheers From mboxrd@z Thu Jan 1 00:00:00 1970 From: michael@ellerman.id.au (Michael Ellerman) Date: Wed, 9 Oct 2013 12:34:37 +1100 Subject: [PATCH RFC 00/77] Re-design MSI/MSI-X interrupts enablement pattern In-Reply-To: <20131008073301.GC10669@dhcp-26-207.brq.redhat.com> References: <20131008043330.GF31666@concordia> <20131008073301.GC10669@dhcp-26-207.brq.redhat.com> Message-ID: <20131009013437.GC23780@concordia> On Tue, Oct 08, 2013@09:33:02AM +0200, Alexander Gordeev wrote: > On Tue, Oct 08, 2013@03:33:30PM +1100, Michael Ellerman wrote: > > On Wed, Oct 02, 2013@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? It's not 19/58, it's 33/58. As to how many we care about on powerpc I can't say, so you have a point there. But I still think the interface is not actually that terrible. cheers From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 9 Oct 2013 12:34:37 +1100 From: Michael Ellerman To: Alexander Gordeev Subject: Re: [PATCH RFC 00/77] Re-design MSI/MSI-X interrupts enablement pattern Message-ID: <20131009013437.GC23780@concordia> References: <20131008043330.GF31666@concordia> <20131008073301.GC10669@dhcp-26-207.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20131008073301.GC10669@dhcp-26-207.brq.redhat.com> Cc: linux-mips@linux-mips.org, "VMware, Inc." , linux-nvme@lists.infradead.org, linux-ide@vger.kernel.org, linux-s390@vger.kernel.org, Andy King , linux-scsi@vger.kernel.org, linux-rdma@vger.kernel.org, x86@kernel.org, Ingo Molnar , linux-pci@vger.kernel.org, iss_storagedev@hp.com, linux-driver@qlogic.com, Tejun Heo , Bjorn Helgaas , Dan Williams , Jon Mason , Solarflare linux maintainers , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Ralf Baechle , e1000-devel@lists.sourceforge.net, Martin Schwidefsky , linux390@de.ibm.com, linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, Oct 08, 2013 at 09:33:02AM +0200, Alexander Gordeev wrote: > 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? It's not 19/58, it's 33/58. As to how many we care about on powerpc I can't say, so you have a point there. But I still think the interface is not actually that terrible. cheers