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/fs/proc/stat.c b/fs/proc/stat.c
index 81904f0..a13431a 100644
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -27,6 +27,7 @@
u64 sum = 0;
struct timespec boottime;
unsigned int per_irq_sum;
+ struct irq_desc *desc;
user = nice = system = idle = iowait =
irq = softirq = steal = cputime64_zero;
@@ -44,10 +45,11 @@
softirq = cputime64_add(softirq, kstat_cpu(i).cpustat.softirq);
steal = cputime64_add(steal, kstat_cpu(i).cpustat.steal);
guest = cputime64_add(guest, kstat_cpu(i).cpustat.guest);
-
- for_each_irq_nr(j)
+ for_each_irq_desc(j, desc) {
+ if (!desc)
+ continue;
sum += kstat_irqs_cpu(j, i);
-
+ }
sum += arch_irq_stat_cpu(i);
}
sum += arch_irq_stat();
@@ -90,11 +92,14 @@
seq_printf(p, "intr %llu", (unsigned long long)sum);
/* sum again ? it could be updated? */
- for_each_irq_nr(j) {
+ for (j = 0; j < NR_IRQS; j++) {
+ desc = irq_to_desc(j);
per_irq_sum = 0;
- for_each_possible_cpu(i)
- per_irq_sum += kstat_irqs_cpu(j, i);
+ if (desc) {
+ for_each_possible_cpu(i)
+ per_irq_sum += kstat_irqs_cpu(j, i);
+ }
seq_printf(p, " %u", per_irq_sum);
}