68 lines
2.3 KiB
Diff
68 lines
2.3 KiB
Diff
From 00a5be1adbbb4886803597dee58cc14af8d4b354 Mon Sep 17 00:00:00 2001
|
|
From: Michal Kubecek <mkubecek@suse.cz>
|
|
Date: Mon, 30 Sep 2013 10:46:09 +0200
|
|
Subject: [PATCH] - patches.fixes/softirq-reduce-latencies.patch: softirq: reduce
|
|
latencies (bnc#797526).
|
|
- patches.fixes/Fix-lockup-related-to-stop_machine-being-stuck-in-__.patch:
|
|
Fix lockup related to stop_machine being stuck in __do_softirq
|
|
(bnc#797526).
|
|
|
|
suse-commit: a4240640b4e07b607003a1bfe9988005817b5db7
|
|
---
|
|
kernel/softirq.c | 23 ++++++++++++++++-------
|
|
1 files changed, 16 insertions(+), 7 deletions(-)
|
|
|
|
diff --git a/kernel/softirq.c b/kernel/softirq.c
|
|
index f773afe..21a8574 100644
|
|
--- a/kernel/softirq.c
|
|
+++ b/kernel/softirq.c
|
|
@@ -194,22 +194,28 @@ void local_bh_enable_ip(unsigned long ip)
|
|
EXPORT_SYMBOL(local_bh_enable_ip);
|
|
|
|
/*
|
|
- * We restart softirq processing MAX_SOFTIRQ_RESTART times,
|
|
- * and we fall back to softirqd after that.
|
|
+ * We restart softirq processing for at most MAX_SOFTIRQ_RESTART times,
|
|
+ * but break the loop if need_resched() is set or after 2 ms.
|
|
+ * The MAX_SOFTIRQ_TIME provides a nice upper bound in most cases, but in
|
|
+ * certain cases, such as stop_machine(), jiffies may cease to
|
|
+ * increment and so we need the MAX_SOFTIRQ_RESTART limit as
|
|
+ * well to make sure we eventually return from this method.
|
|
*
|
|
- * This number has been established via experimentation.
|
|
+ * These limits have been established via experimentation.
|
|
* The two things to balance is latency against fairness -
|
|
* we want to handle softirqs as soon as possible, but they
|
|
* should not be able to lock up the box.
|
|
*/
|
|
+#define MAX_SOFTIRQ_TIME msecs_to_jiffies(2)
|
|
#define MAX_SOFTIRQ_RESTART 10
|
|
|
|
asmlinkage void __do_softirq(void)
|
|
{
|
|
struct softirq_action *h;
|
|
__u32 pending;
|
|
- int max_restart = MAX_SOFTIRQ_RESTART;
|
|
+ unsigned long end = jiffies + MAX_SOFTIRQ_TIME;
|
|
int cpu;
|
|
+ int max_restart = MAX_SOFTIRQ_RESTART;
|
|
|
|
pending = local_softirq_pending();
|
|
account_system_vtime(current);
|
|
@@ -257,11 +264,13 @@ restart:
|
|
local_irq_disable();
|
|
|
|
pending = local_softirq_pending();
|
|
- if (pending && --max_restart)
|
|
- goto restart;
|
|
+ if (pending) {
|
|
+ if (time_before(jiffies, end) && !need_resched() &&
|
|
+ --max_restart)
|
|
+ goto restart;
|
|
|
|
- if (pending)
|
|
wakeup_softirqd();
|
|
+ }
|
|
|
|
lockdep_softirq_exit();
|