[RFC 3/6] softirq: Add reverse group-to-softirq map

Dmitry Safonov
2018-01-18T16:12:53Z

For faster operation with pending mask:
pending &= group_to_softirq[group_nr];

Signed-off-by: Dmitry Safonov <dima@arista.com>
---
kernel/softirq.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)

diff --git a/kernel/softirq.c b/kernel/softirq.c
index ca8c3db4570d..7de5791c08f9 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -54,6 +54,7 @@ EXPORT_SYMBOL(irq_stat);
#endif

static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp;
+static unsigned group_to_softirqs[sizeof(softirq_vec[0].group_mask)] __cacheline_aligned_in_smp;
static unsigned __initdata nr_softirq_groups = 0;

DEFINE_PER_CPU(struct task_struct *, ksoftirqd);
@@ -650,11 +651,28 @@ static void __init setup_default_softirq_group(unsigned nr)
}
}

+static void __init fill_group_to_softirq_maps(void)
+{
+ unsigned i;
+
+ for (i = 0; i < NR_SOFTIRQS; i++) {
+ u32 mask = softirq_vec[i].group_mask;
+ unsigned j, group = 0;
+
+ while ((j = ffs(mask))) {
+ group += j - 1;
+ group_to_softirqs[group] |= (1 << i);
+ mask >>= j;
+ }
+ }
+}
+
void __init softirq_init(void)
{
int cpu;

setup_default_softirq_group(nr_softirq_groups++);
+ fill_group_to_softirq_maps();

for_each_possible_cpu(cpu) {
per_cpu(tasklet_vec, cpu).tail =
--
2.13.6