From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel J Blueman Subject: Re: [Patch Part3 v4 38/38] x86, irq: Add kernel parameter vector_alloc to set CPU vector allocation policy Date: Mon, 01 Dec 2014 14:15:52 -0500 Message-ID: <547CBE68.1040704@numascale.com> References: <1416901802-24211-1-git-send-email-jiang.liu@linux.intel.com> <1416901802-24211-39-git-send-email-jiang.liu@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-pci-owner@vger.kernel.org To: Bjorn Helgaas , Jiang Liu Cc: Benjamin Herrenschmidt , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , "Rafael J. Wysocki" , Randy Dunlap , Yinghai Lu , Borislav Petkov , Jonathan Corbet , "x86@kernel.org" , Konrad Rzeszutek Wilk , Andrew Morton , Tony Luck , Joerg Roedel , Greg Kroah-Hartman , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "linux-doc@vger.kernel.org" List-Id: linux-acpi@vger.kernel.org On 12/01/2014 01:49 PM, Bjorn Helgaas wrote: > On Tue, Nov 25, 2014 at 12:50 AM, Jiang Liu wrote: >> Parameter vector_alloc should be set to an integer with: >> bit 0: enable allocating CPU vector from CPUs on device local node. >> That's to allocate from cpumask_of_node(irq_data->node). >> bit 1: enable the default policy, which is to allocate from >> apic->target_cpus(). >> >> When allocating vectors, it tries all enabled policies from lower bit >> position to higher bit position. >> >> This option could be use to optimize interrupt distribution on large >> system such as NumaChip etc. > > Why can't we figure this out automatically? Having a kernel parameter > is a pain in the neck for users. For the Numachip case, it would be sufficient to add a call to set_vector_alloc_policy in the APIC driver, as this will always be preferred for local MSI handling. I'll follow up with a patch in the next day or so; further support for other systems can be added later as and when tested. >> Signed-off-by: Jiang Liu >> Cc: Daniel J Blueman >> --- >> Documentation/kernel-parameters.txt | 6 ++++++ >> arch/x86/kernel/apic/vector.c | 11 +++++++++++ >> 2 files changed, 17 insertions(+) >> >> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt >> index 4c81a860cc2b..a175c5016954 100644 >> --- a/Documentation/kernel-parameters.txt >> +++ b/Documentation/kernel-parameters.txt >> @@ -3709,6 +3709,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. >> vector= [IA-64,SMP] >> vector=percpu: enable percpu vector domain >> >> + vector_alloc= [x86,SMP] >> + vector_alloc=policy: policy is a bitmap, bit 0 >> + for allocating CPU vector from CPUs on device local >> + node; bit 1 for the default policy to allocating from >> + apic->target_cpus(). All higher bits are reserved. >> + >> video= [FB] Frame buffer configuration >> See Documentation/fb/modedb.txt. >> >> diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c >> index 16de8906ee1e..1158843551c7 100644 >> --- a/arch/x86/kernel/apic/vector.c >> +++ b/arch/x86/kernel/apic/vector.c >> @@ -79,6 +79,17 @@ void set_vector_alloc_policy(unsigned int policy) >> x86_vector_alloc_policy = policy | X86_VECTOR_POL_CALLER; >> } >> >> +static int __init apic_parse_vector_policy(char *str) >> +{ >> + int policy; >> + >> + if (get_option(&str, &policy) == 1) >> + set_vector_alloc_policy(policy); >> + >> + return 1; >> +} >> +__setup("vector_alloc=", apic_parse_vector_policy); >> + >> static struct apic_chip_data *alloc_apic_chip_data(int node) >> { >> struct apic_chip_data *data; -- Daniel J Blueman Principal Software Engineer, Numascale