On 02/01/2012 04:15 PM, Daniel Lezcano wrote:
Yes, but the problem is the same also. Did you try
by removing atomic_inc and set nrunnings to nrkthread ?
Unfortunately it's still here:
Unable to handle kernel paging request at virtual address 7f0a411c
pgd = 80004000
[7f0a411c] *pgd=bf163811, *pte=00000000, *ppte=00000000
Internal error: Oops: 80000007 [#1] PREEMPT SMP
Modules linked in: [last unloaded: testmod]
CPU: 0 Tainted: G O (3.3.0-rc2+ #2)
PC is at 0x7f0a411c
LR is at __schedule+0x684/0x6e4
pc : [<7f0a411c>] lr : [<802c0bdc>] psr: 600f0113
sp : bf3b5f78 ip : 00000000 fp : 00000000
r10: 00000000 r9 : 00000000 r8 : 7f0a4538
r7 : 00000002 r6 : 00000400 r5 : 0000003c r4 : 00000001
r3 : 00000000 r2 : bf3b5eb0 r1 : bf219580 r0 : 00000001
Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment kernel
Control: 10c5387d Table: bfbec04a DAC: 00000015
Process test/124 (pid: 6772, stack limit = 0xbf3b42f8)
Stack: (0xbf3b5f78 to 0xbf3b6000)
5f60: 7b11940d 0000003c
5f80: 000f4240 00000000 00000001 000b07b6 bf8c9e44 00000000 7f0a4000 00000013
5fa0: 00000000 80049260 00000000 00000000 00000000 00000000 00000000 00000000
5fc0: dead4ead ffffffff ffffffff 8048b2b8 00000000 00000000 8036a4d9 bf3b5fdc
5fe0: bf3b5fdc 271aee1c bf8c9e44 800491d4 8000eabc 8000eabc bfefc811 bfefcc11
Code: bad PC value
If someone wants to look at it, I'm attaching everything. The patch is almost
nothing beyond
exporting irq_time_read() to modules.
Note it's quite rare - to reproduce it, I do
while true; do insmod testmod.ko usehrtime=1 && rmmod testmod.ko; sleep 1; done
and wait for a few minutes.
Dmitry
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/kthread.h>
#include <linux/hardirq.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/ktime.h>
MODULE_LICENSE("GPL");
static int nrthreads = 128;
module_param(nrthreads, int, 0644);
static int loopcount = 1024;
module_param(loopcount, int, 0644);
static int usehrtime = 0;
module_param(usehrtime, int, 0644);
static int slack = 50000;
module_param(slack, int, 0644);
static int msecs = 1;
module_param(msecs, int, 0644);
static DEFINE_PER_CPU(u64, cpu_irq_time);
static DECLARE_COMPLETION(done);
static struct task_struct **threads;
static atomic_t nrunning;
static ktime_t start;
static void timeout_init_irq_time(void *unused)
{
int cpu = smp_processor_id();
per_cpu(cpu_irq_time, cpu) = irq_time_read(cpu);
}
static void timeout_show_irq_time(void *unused)
{
int cpu = smp_processor_id();
u64 irqtime = irq_time_read(cpu) - per_cpu(cpu_irq_time, cpu);
printk("cpu%d spent %llu usecs in irqs\n",
cpu, div64_u64(irqtime, NSEC_PER_USEC));
}
static int test(void *unused)
{
int i;
ktime_t expires = ktime_set(0, msecs * NSEC_PER_MSEC);
for (i = 0; !kthread_should_stop() && i < loopcount; i++) {
if (usehrtime) {
set_current_state(TASK_UNINTERRUPTIBLE);
schedule_hrtimeout_range(&expires, slack,
HRTIMER_MODE_REL);
}
else
schedule_timeout_uninterruptible(msecs_to_jiffies(msecs));
}
if (atomic_dec_and_test(&nrunning)) {
on_each_cpu(timeout_show_irq_time, NULL, 1);
printk("-- timeout test end, %lld msecs elapsed --\n",
ktime_to_ms(ktime_sub(ktime_get(), start)));
complete(&done);
}
return 0;
}
static int __init testmod_init(void)
{
int i;
printk("-- %d-threads, %d-loops timeout test for %d-msecs timeouts, use
%s",
nrthreads, loopcount, msecs,
(usehrtime ? "high-res timeout " : "jiffies timeout "));
if (usehrtime)
printk("with %u-nsecs slack --\n", slack);
else
printk("--\n");
start = ktime_get();
atomic_set(&nrunning, nrthreads);
on_each_cpu(timeout_init_irq_time, NULL, 1);
threads = kmalloc(nrthreads * sizeof(struct task_struct *), GFP_KERNEL);
if (!threads)
return -ENOMEM;
for (i = 0; i < nrthreads; i++) {
threads[i] = kthread_run(test, NULL, "test/%d", i);
if (IS_ERR(threads[i])) {
int j, err = PTR_ERR(threads[i]);
for (j = 0; j < i; j++)
kthread_stop(threads[j]);
kfree(threads);
return err;
}
}
return 0;
}
static void __exit testmod_exit(void)
{
wait_for_completion(&done);
kfree(threads);
}
module_init(testmod_init);
module_exit(testmod_exit);
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 5bed94e..4759676 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -805,17 +805,6 @@ config SCHED_MC
making when dealing with multi-core CPU chips at a cost of slightly
increased overhead in some places. If unsure say N here.
-config IRQ_TIME_ACCOUNTING
- bool "Fine granularity task level IRQ time accounting"
- default n
- ---help---
- Select this option to enable fine granularity task irq time
- accounting. This is done by reading a timestamp on each
- transitions between softirq and hardirq state, so there can be a
- small performance impact.
-
- If in doubt, say N here.
-
source "kernel/Kconfig.preempt"
config X86_UP_APIC
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index bb7f309..3d08f8d 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -137,6 +137,7 @@ static inline void account_system_vtime(struct task_struct
*tsk)
}
#else
extern void account_system_vtime(struct task_struct *tsk);
+extern u64 irq_time_read(int cpu);
#endif
#if defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index df00cb0..b033d78 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -762,7 +762,7 @@ static DEFINE_PER_CPU(u64, cpu_hardirq_time);
static DEFINE_PER_CPU(u64, cpu_softirq_time);
static DEFINE_PER_CPU(u64, irq_start_time);
-static int sched_clock_irqtime;
+static int sched_clock_irqtime = 1;
void enable_sched_clock_irqtime(void)
{
@@ -789,7 +789,7 @@ static inline void irq_time_write_end(void)
__this_cpu_inc(irq_time_seq.sequence);
}
-static inline u64 irq_time_read(int cpu)
+u64 __sched irq_time_read(int cpu)
{
u64 irq_time;
unsigned seq;
@@ -811,12 +811,14 @@ static inline void irq_time_write_end(void)
{
}
-static inline u64 irq_time_read(int cpu)
+u64 __sched irq_time_read(int cpu)
{
return per_cpu(cpu_softirq_time, cpu) + per_cpu(cpu_hardirq_time, cpu);
}
#endif /* CONFIG_64BIT */
+EXPORT_SYMBOL(irq_time_read);
+
/*
* Called before incrementing preempt_count on {soft,}irq_enter
* and before decrementing preempt_count on {soft,}irq_exit.
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 8745ac7..d6d7afc 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -299,6 +299,17 @@ config SCHEDSTATS
application, you can say N to avoid the very slight overhead
this adds.
+config IRQ_TIME_ACCOUNTING
+ bool "Fine granularity task level IRQ time accounting"
+ default n
+ ---help---
+ Select this option to enable fine granularity task irq time
+ accounting. This is done by reading a timestamp on each
+ transitions between softirq and hardirq state, so there can be a
+ small performance impact.
+
+ If in doubt, say N here.
+
config TIMER_STATS
bool "Collect kernel timers statistics"
depends on DEBUG_KERNEL && PROC_FS
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