diff options
| author | Joe Perches <joe@perches.com> | 2014-01-27 17:07:14 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-01-27 21:02:40 -0800 |
| commit | 2e702b9f6cba4eb87d90e2a2d425a1fc05eec803 (patch) | |
| tree | ade4a3bcec477ced2780f1841e7c06f547effe84 | |
| parent | a19428e5c3f4f39c302cb97b847dfd23613145c1 (diff) | |
softirq: use ffs() in __do_softirq()
Possible speed improvement of __do_softirq() by using ffs() instead of
using a while loop with an & 1 test then single bit shift.
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | kernel/softirq.c | 43 |
1 files changed, 22 insertions, 21 deletions
diff --git a/kernel/softirq.c b/kernel/softirq.c index 8a1e6e104892..ba79bbfe380e 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -229,6 +229,7 @@ asmlinkage void __do_softirq(void) struct softirq_action *h; bool in_hardirq; __u32 pending; + int softirq_bit; int cpu; /* @@ -253,30 +254,30 @@ restart: h = softirq_vec; - do { - if (pending & 1) { - unsigned int vec_nr = h - softirq_vec; - int prev_count = preempt_count(); - - kstat_incr_softirqs_this_cpu(vec_nr); - - trace_softirq_entry(vec_nr); - h->action(h); - trace_softirq_exit(vec_nr); - if (unlikely(prev_count != preempt_count())) { - printk(KERN_ERR "huh, entered softirq %u %s %p" - "with preempt_count %08x," - " exited with %08x?\n", vec_nr, - softirq_to_name[vec_nr], h->action, - prev_count, preempt_count()); - preempt_count_set(prev_count); - } + while ((softirq_bit = ffs(pending))) { + unsigned int vec_nr; + int prev_count; + + h += softirq_bit - 1; + + vec_nr = h - softirq_vec; + prev_count = preempt_count(); - rcu_bh_qs(cpu); + kstat_incr_softirqs_this_cpu(vec_nr); + + trace_softirq_entry(vec_nr); + h->action(h); + trace_softirq_exit(vec_nr); + if (unlikely(prev_count != preempt_count())) { + printk(KERN_ERR "huh, entered softirq %u %s %p with preempt_count %08x, exited with %08x?\n", + vec_nr, softirq_to_name[vec_nr], h->action, + prev_count, preempt_count()); + preempt_count_set(prev_count); } + rcu_bh_qs(cpu); h++; - pending >>= 1; - } while (pending); + pending >>= softirq_bit; + } local_irq_disable(); |