Subject: + softirq-use-ffs-in-__do_softirq.patch added to -mm tree
To: joe@xxxxxxxxxxx,fweisbec@xxxxxxxxx,mingo@xxxxxxx,tglx@xxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 10 Dec 2013 15:54:25 -0800
The patch titled
Subject: softirq: use ffs() in __do_softirq()
has been added to the -mm tree. Its filename is
softirq-use-ffs-in-__do_softirq.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/softirq-use-ffs-in-__do_softirq.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/softirq-use-ffs-in-__do_softirq.patch
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------------------------------------------------------
From: Joe Perches <joe@xxxxxxxxxxx>
Subject: 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@xxxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/softirq.c | 45 +++++++++++++++++++++++----------------------
1 file changed, 23 insertions(+), 22 deletions(-)
diff -puN kernel/softirq.c~softirq-use-ffs-in-__do_softirq kernel/softirq.c
--- a/kernel/softirq.c~softirq-use-ffs-in-__do_softirq
+++ a/kernel/softirq.c
@@ -219,6 +219,7 @@ asmlinkage void __do_softirq(void)
int cpu;
unsigned long old_flags = current->flags;
int max_restart = MAX_SOFTIRQ_RESTART;
+ int softirq_bit;
/*
* Mask out PF_MEMALLOC s current task context is borrowed for the
@@ -242,30 +243,30 @@ 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);
- }
-
- rcu_bh_qs(cpu);
+ 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();
+
+ 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();
_
Patches currently in -mm which might be from joe@xxxxxxxxxxx are
softirq-use-ffs-in-__do_softirq.patch
softirq-convert-printks-to-pr_level.patch
softirq-use-const-char-const-for-softirq_to_name-whitespace-neatening.patch
lib-parserc-add-match_wildcard-function.patch
lib-parserc-put-export_symbols-in-the-conventional-place.patch
dynamic_debug-add-wildcard-support-to-filter-files-functions-modules.patch
dynamic-debug-howtotxt-update-since-new-wildcard-support.patch
printk-cache-mark-printk_once-test-variable-__read_mostly.patch
printk-cache-mark-printk_once-test-variable-__read_mostly-fix.patch
vsprintf-add-%pad-extension-for-dma_addr_t-use.patch
get_maintainer-add-commit-author-information-to-rolestats.patch
test-add-minimal-module-for-verification-testing.patch
test-check-copy_to-from_user-boundary-validation.patch
checkpatchpl-check-for-function-declarations-without-arguments.patch
checkpatch-more-comprehensive-split-strings-warning.patch
checkpatch-warn-only-on-space-before-semicolon-at-end-of-line.patch
linux-next.patch
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