Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756095Ab3IZJUy (ORCPT ); Thu, 26 Sep 2013 05:20:54 -0400 Received: from mx0.aculab.com ([213.249.233.131]:37584 "HELO mx0.aculab.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751471Ab3IZJUu convert rfc822-to-8bit (ORCPT ); Thu, 26 Sep 2013 05:20:50 -0400 x-mimeole: Produced By Microsoft Exchange V6.5 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: 8BIT Subject: RE: [PATCH v2 2/6] PCI/MSI: Factor out pci_get_msi_cap() interface Date: Thu, 26 Sep 2013 09:58:53 +0100 Message-ID: In-Reply-To: <20130926074646.GA16774@dhcp-26-207.brq.redhat.com> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [PATCH v2 2/6] PCI/MSI: Factor out pci_get_msi_cap() interface Thread-Index: Ac66jCExPXWbbw9rSKaYZ0jtRX1gRQACddJQ References: <20130916102210.GA14102@dhcp-26-207.brq.redhat.com> <20130917143022.GA7707@concordia> <20130918094759.GA2353@dhcp-26-207.brq.redhat.com> <20130918142231.GA21650@mtj.dyndns.org> <20130918165045.GB2353@dhcp-26-207.brq.redhat.com> <20130920082458.GA10507@dhcp-26-207.brq.redhat.com> <20130920122736.GD7630@mtj.dyndns.org> <20130925180220.GB26273@google.com> <20130925205804.GA21737@dhcp-26-207.brq.redhat.com> <20130925210016.GA8926@htj.dyndns.org> <20130926074646.GA16774@dhcp-26-207.brq.redhat.com> From: "David Laight" To: "Alexander Gordeev" , "Tejun Heo" Cc: , "Joerg Roedel" , , , , "Jan Beulich" , "Bjorn Helgaas" , , "Ingo Molnar" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1386 Lines: 33 > Subject: Re: [PATCH v2 2/6] PCI/MSI: Factor out pci_get_msi_cap() interface > > On Wed, Sep 25, 2013 at 05:00:16PM -0400, Tejun Heo wrote: > > Hello, > > > > On Wed, Sep 25, 2013 at 10:58:05PM +0200, Alexander Gordeev wrote: > > > Unfortunately, pSeries is a shows-topper here :( It seems we have to > > > introduce pci_get_msi{,x}_limit() interfaces to honour the quota > > > thing. I just hope the hardware set for pSeries is limited and we > > > won't need to use it for all drivers. > > > > Can you please go into a bit of detail on that? Why does it matter? > > Because otherwise we will re-introduce a problem described by Michael: > "We have a small number of MSIs available, limited by hardware & > firmware, if we don't impose a quota then the first device that probes > will get most/all of the MSIs and other devices miss out." Would it be possible to do some kind of 2-stage allocation. In the first pass the driver would pass a minimum and desired number of MSI-X interrupts, but not actually be given any. Interrupts could then be allocated after it is known how many are required and how many are available. David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/