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sparse irq_desc[] array: core kernel and x86 changes

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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>
This commit is contained in:
Yinghai Lu
2008-12-05 18:58:31 -08:00
committed by Ingo Molnar
parent 218d11a8b0
commit 0b8f1efad3
23 changed files with 659 additions and 173 deletions
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17
fs/proc/stat.c
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@ -27,6 +27,7 @@ static int show_stat(struct seq_file *p, void *v)
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 @@ static int show_stat(struct seq_file *p, void *v)
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 @@ static int show_stat(struct seq_file *p, void *v)
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);
}