Commit d872818d authored by Suresh Siddha's avatar Suresh Siddha Committed by Ingo Molnar

x86/apic/x2apic: Use multiple cluster members for the irq destination only...

x86/apic/x2apic: Use multiple cluster members for the irq destination only with the explicit affinity

During boot or driver load etc, interrupt destination is setup
using default target cpu's. Later the user (irqbalance etc) or
the driver (irq_set_affinity/ irq_set_affinity_hint) can request
the interrupt to be migrated to some specific set of cpu's.

In the x2apic cluster routing, for the default scenario use
single cpu as the interrupt destination and when there is an
explicit interrupt affinity request, route the interrupt to
multiple members of a x2apic cluster specified in the cpumask of
the migration request.

This will minmize the vector pressure when there are lot of
interrupt sources and relatively few x2apic clusters (for
example a single socket server). This will allow the performance
critical interrupts to be routed to multiple cpu's in the x2apic
cluster (irqbalance for example uses the cache siblings etc
while specifying the interrupt destination) and allow
non-critical interrupts to be serviced by a single logical cpu.
Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Acked-by: default avatarYinghai Lu <yinghai@kernel.org>
Acked-by: default avatarAlexander Gordeev <agordeev@redhat.com>
Acked-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
Link: http://lkml.kernel.org/r/1340656709-11423-4-git-send-email-suresh.b.siddha@intel.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 1ac322d0
...@@ -209,13 +209,30 @@ static int x2apic_cluster_probe(void) ...@@ -209,13 +209,30 @@ static int x2apic_cluster_probe(void)
return 0; return 0;
} }
static const struct cpumask *x2apic_cluster_target_cpus(void)
{
return cpu_all_mask;
}
/* /*
* Each x2apic cluster is an allocation domain. * Each x2apic cluster is an allocation domain.
*/ */
static void cluster_vector_allocation_domain(int cpu, struct cpumask *retmask, static void cluster_vector_allocation_domain(int cpu, struct cpumask *retmask,
const struct cpumask *mask) const struct cpumask *mask)
{ {
cpumask_and(retmask, mask, per_cpu(cpus_in_cluster, cpu)); /*
* To minimize vector pressure, default case of boot, device bringup
* etc will use a single cpu for the interrupt destination.
*
* On explicit migration requests coming from irqbalance etc,
* interrupts will be routed to the x2apic cluster (cluster-id
* derived from the first cpu in the mask) members specified
* in the mask.
*/
if (mask == x2apic_cluster_target_cpus())
cpumask_copy(retmask, cpumask_of(cpu));
else
cpumask_and(retmask, mask, per_cpu(cpus_in_cluster, cpu));
} }
static struct apic apic_x2apic_cluster = { static struct apic apic_x2apic_cluster = {
...@@ -229,7 +246,7 @@ static struct apic apic_x2apic_cluster = { ...@@ -229,7 +246,7 @@ static struct apic apic_x2apic_cluster = {
.irq_delivery_mode = dest_LowestPrio, .irq_delivery_mode = dest_LowestPrio,
.irq_dest_mode = 1, /* logical */ .irq_dest_mode = 1, /* logical */
.target_cpus = online_target_cpus, .target_cpus = x2apic_cluster_target_cpus,
.disable_esr = 0, .disable_esr = 0,
.dest_logical = APIC_DEST_LOGICAL, .dest_logical = APIC_DEST_LOGICAL,
.check_apicid_used = NULL, .check_apicid_used = NULL,
......
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