linux-kernel - Re: [Patch Part3 v4 38/38] x86, irq: Add kernel parameter vector_alloc to set CPU vector allocation policy

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <547CBE68.1040704@numascale.com>
Date:	Mon, 01 Dec 2014 14:15:52 -0500
From:	Daniel J Blueman <daniel@...ascale.com>
To:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Jiang Liu <jiang.liu@...ux.intel.com>
CC:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Randy Dunlap <rdunlap@...radead.org>,
	Yinghai Lu <yinghai@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Jonathan Corbet <corbet@....net>,
	"x86@...nel.org" <x86@...nel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tony Luck <tony.luck@...el.com>,
	Joerg Roedel <joro@...tes.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>
Subject: Re: [Patch Part3 v4 38/38] x86, irq: Add kernel parameter vector_alloc
 to set CPU vector allocation policy

On 12/01/2014 01:49 PM, Bjorn Helgaas wrote:
> On Tue, Nov 25, 2014 at 12:50 AM, Jiang Liu <jiang.liu@...ux.intel.com> 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 <jiang.liu@...ux.intel.com>
>> Cc: Daniel J Blueman <daniel@...ascale.com>
>> ---
>>   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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/