sparse irq_desc[] array: core kernel and x86 changes
Impact: new feature
Problem on distro kernels: irq_desc[NR_IRQS] takes megabytes of RAM with
NR_CPUS set to large values. The goal is to be able to scale up to much
larger NR_IRQS value without impacting the (important) common case.
To solve this, we generalize irq_desc[NR_IRQS] to an (optional) array of
irq_desc pointers.
When CONFIG_SPARSE_IRQ=y is used, we use kzalloc_node to get irq_desc,
this also makes the IRQ descriptors NUMA-local (to the site that calls
request_irq()).
This gets rid of the irq_cfg[] static array on x86 as well: irq_cfg now
uses desc->chip_data for x86 to store irq_cfg.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/init/main.c b/init/main.c
index 7e117a2..c1f999a 100644
--- a/init/main.c
+++ b/init/main.c
@@ -539,6 +539,15 @@
{
}
+void __init __weak arch_early_irq_init(void)
+{
+}
+
+void __init __weak early_irq_init(void)
+{
+ arch_early_irq_init();
+}
+
asmlinkage void __init start_kernel(void)
{
char * command_line;
@@ -603,6 +612,8 @@
sort_main_extable();
trap_init();
rcu_init();
+ /* init some links before init_ISA_irqs() */
+ early_irq_init();
init_IRQ();
pidhash_init();
init_timers();