Messages in this thread | | | Date | Mon, 01 Dec 2014 14:15:52 -0500 | From | Daniel J Blueman <> | 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@linux.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@linux.intel.com> >> Cc: Daniel J Blueman <daniel@numascale.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
| |