| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Wed, 27 Nov 2013 14:43:45 +0100
From: Juri Lelli <juri.lelli@...il.com>
To: Steven Rostedt <rostedt@...dmis.org>
CC: peterz@...radead.org, tglx@...utronix.de, mingo@...hat.com,
oleg@...hat.com, fweisbec@...il.com, darren@...art.com,
johan.eker@...csson.com, p.faure@...tech.ch,
linux-kernel@...r.kernel.org, claudio@...dence.eu.com,
michael@...rulasolutions.com, fchecconi@...il.com,
tommaso.cucinotta@...up.it, nicola.manica@...i.unitn.it,
luca.abeni@...tn.it, dhaval.giani@...il.com, hgu1972@...il.com,
paulmck@...ux.vnet.ibm.com, raistlin@...ux.it,
insop.song@...il.com, liming.wang@...driver.com, jkacur@...hat.com,
harald.gustafsson@...csson.com, vincent.guittot@...aro.org,
bruce.ashfield@...driver.com
Subject: Re: [PATCH 08/14] sched: add latency tracing for -deadline tasks.
On 11/20/2013 10:33 PM, Steven Rostedt wrote:
> On Thu, 7 Nov 2013 14:43:42 +0100
> Juri Lelli <juri.lelli@...il.com> wrote:
>
>
>> + /*
>> + * Semantic is like this:
>> + * - wakeup tracer handles all tasks in the system, independently
>> + * from their scheduling class;
>> + * - wakeup_rt tracer handles tasks belonging to sched_dl and
>> + * sched_rt class;
>> + * - wakeup_dl handles tasks belonging to sched_dl class only.
>> + */
>> + if ((wakeup_dl && !dl_task(p)) ||
>> + (wakeup_rt && !dl_task(p) && !rt_task(p)) ||
>> + (p->prio >= wakeup_prio || p->prio >= current->prio))
>> return;
>>
>> pc = preempt_count();
>> @@ -486,7 +495,7 @@ probe_wakeup(void *ignore, struct task_struct *p, int success)
>> arch_spin_lock(&wakeup_lock);
>>
>> /* check for races. */
>> - if (!tracer_enabled || p->prio >= wakeup_prio)
>> + if (!tracer_enabled || (!dl_task(p) && p->prio >= wakeup_prio))
>> goto out_locked;
>
> We probably want to add a "tracing_dl" variable, and do the test like
> this:
>
> if (!tracer_enabled || tracing_dl ||
> (!dl_task(p) && p->prio >= wakeup_prio))
>
> and for the first if statement too. Otherwise if two dl tasks are
> running on two different CPUs, the second will override the first. Once
> you start tracing a dl_task, you shouldn't bother tracing another task
> until that one wakes up.
>
> if (dl_task(p))
> tracing_dl = 1;
> else
> tracing_dl = 0;
>
Ok, this fixes the build error:
--------------------------------------
kernel/trace/trace_selftest.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index f76f8d6..ad94604 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -1023,16 +1023,16 @@ trace_selftest_startup_nop(struct tracer *trace, struct trace_array *tr)
static int trace_wakeup_test_thread(void *data)
{
/* Make this a -deadline thread */
- struct sched_param2 paramx = {
+ static const struct sched_param2 param = {
.sched_priority = 0,
+ .sched_flags = 0,
.sched_runtime = 100000ULL,
.sched_deadline = 10000000ULL,
.sched_period = 10000000ULL
- .sched_flags = 0
};
struct completion *x = data;
- sched_setscheduler2(current, SCHED_DEADLINE, ¶mx);
+ sched_setscheduler2(current, SCHED_DEADLINE, ¶m);
/* Make it know we have a new prio */
complete(x);
@@ -1088,19 +1088,19 @@ trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
while (p->on_rq) {
/*
- * Sleep to make sure the RT thread is asleep too.
+ * Sleep to make sure the -deadline thread is asleep too.
* On virtual machines we can't rely on timings,
* but we want to make sure this test still works.
*/
msleep(100);
}
- init_completion(&isrt);
+ init_completion(&is_ready);
wake_up_process(p);
/* Wait for the task to wake up */
- wait_for_completion(&isrt);
+ wait_for_completion(&is_ready);
/* stop the tracing. */
tracing_stop();
--------------------------------
And this should implement what you were asking for:
--------------------------------
kernel/trace/trace_sched_wakeup.c | 28 ++++++++++++++++++++++++----
1 file changed, 24 insertions(+), 4 deletions(-)
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 1457fb1..090c4d9 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -28,6 +28,7 @@ static int wakeup_current_cpu;
static unsigned wakeup_prio = -1;
static int wakeup_rt;
static int wakeup_dl;
+static int tracing_dl = 0;
static arch_spinlock_t wakeup_lock =
(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
@@ -438,6 +439,7 @@ static void __wakeup_reset(struct trace_array *tr)
{
wakeup_cpu = -1;
wakeup_prio = -1;
+ tracing_dl = 0;
if (wakeup_task)
put_task_struct(wakeup_task);
@@ -481,9 +483,9 @@ probe_wakeup(void *ignore, struct task_struct *p, int success)
* sched_rt class;
* - wakeup_dl handles tasks belonging to sched_dl class only.
*/
- if ((wakeup_dl && !dl_task(p)) ||
+ if (tracing_dl || (wakeup_dl && !dl_task(p)) ||
(wakeup_rt && !dl_task(p) && !rt_task(p)) ||
- (p->prio >= wakeup_prio || p->prio >= current->prio))
+ (!dl_task(p) && (p->prio >= wakeup_prio || p->prio >= current->prio)))
return;
pc = preempt_count();
@@ -495,7 +497,8 @@ probe_wakeup(void *ignore, struct task_struct *p, int success)
arch_spin_lock(&wakeup_lock);
/* check for races. */
- if (!tracer_enabled || (!dl_task(p) && p->prio >= wakeup_prio))
+ if (!tracer_enabled || tracing_dl ||
+ (!dl_task(p) && p->prio >= wakeup_prio))
goto out_locked;
/* reset the trace */
@@ -505,6 +508,15 @@ probe_wakeup(void *ignore, struct task_struct *p, int success)
wakeup_current_cpu = wakeup_cpu;
wakeup_prio = p->prio;
+ /*
+ * Once you start tracing a -deadline task, don't bother tracing
+ * another task until the first one wakes up.
+ */
+ if (dl_task(p))
+ tracing_dl = 1;
+ else
+ tracing_dl = 0;
+
wakeup_task = p;
get_task_struct(wakeup_task);
@@ -700,10 +712,18 @@ static struct tracer wakeup_dl_tracer __read_mostly =
.start = wakeup_tracer_start,
.stop = wakeup_tracer_stop,
.wait_pipe = poll_wait_pipe,
- .print_max = 1,
+ .print_max = true,
+ .print_header = wakeup_print_header,
+ .print_line = wakeup_print_line,
+ .flags = &tracer_flags,
+ .set_flag = wakeup_set_flag,
+ .flag_changed = wakeup_flag_changed,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_wakeup,
#endif
+ .open = wakeup_trace_open,
+ .close = wakeup_trace_close,
+ .use_max_tr = true,
};
__init static int init_wakeup_tracer(void)
-----------------------------------
Makes sense? :)
Thanks,
- Juri
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists