* [PATCH] kernel: trace: preemptirq_delay_test: add cpu affinity
@ 2021-01-28 1:35 Song Chen
2021-01-29 22:22 ` Steven Rostedt
0 siblings, 1 reply; 2+ messages in thread
From: Song Chen @ 2021-01-28 1:35 UTC (permalink / raw)
To: rostedt, mingo, linux-kernel, linux-rt-users; +Cc: Song Chen
The kernel thread executing test can run on any cpu, which might be
different cpu latency tracer is running on, as a result, the
big latency caused by preemptirq delay test can't be detected.
Therefore, the argument cpu_affinity is added to be passed to test,
ensure it's running on the same cpu with latency tracer.
e.g.
cyclictest -p 90 -m -c 0 -i 1000 -a 3
modprobe preemptirq_delay_test test_mode=preempt delay=500 \
burst_size=3 cpu_affinity=3
Signed-off-by: Song Chen <chensong_2000@189.cn>
---
kernel/trace/Kconfig | 4 ++++
kernel/trace/preemptirq_delay_test.c | 14 ++++++++++++++
2 files changed, 18 insertions(+)
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index c1a62ae..44dd5c0 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -886,6 +886,10 @@ config PREEMPTIRQ_DELAY_TEST
irq-disabled critical sections for 500us:
modprobe preemptirq_delay_test test_mode=irq delay=500 burst_size=3
+ What's more, if you want to attach the test on the cpu which the latency
+ tracer is running on, specify cpu_affinity=cpu_num at the end of the
+ command.
+
If unsure, say N
config SYNTH_EVENT_GEN_TEST
diff --git a/kernel/trace/preemptirq_delay_test.c b/kernel/trace/preemptirq_delay_test.c
index 312d1a0..8c4ffd0 100644
--- a/kernel/trace/preemptirq_delay_test.c
+++ b/kernel/trace/preemptirq_delay_test.c
@@ -21,13 +21,16 @@
static ulong delay = 100;
static char test_mode[12] = "irq";
static uint burst_size = 1;
+static int cpu_affinity = -1;
module_param_named(delay, delay, ulong, 0444);
module_param_string(test_mode, test_mode, 12, 0444);
module_param_named(burst_size, burst_size, uint, 0444);
+module_param_named(cpu_affinity, cpu_affinity, int, 0444);
MODULE_PARM_DESC(delay, "Period in microseconds (100 us default)");
MODULE_PARM_DESC(test_mode, "Mode of the test such as preempt, irq, or alternate (default irq)");
MODULE_PARM_DESC(burst_size, "The size of a burst (default 1)");
+MODULE_PARM_DESC(cpu_affinity, "Cpu num test is running on");
static struct completion done;
@@ -36,7 +39,9 @@ static struct completion done;
static void busy_wait(ulong time)
{
u64 start, end;
+
start = trace_clock_local();
+
do {
end = trace_clock_local();
if (kthread_should_stop())
@@ -47,6 +52,7 @@ static void busy_wait(ulong time)
static __always_inline void irqoff_test(void)
{
unsigned long flags;
+
local_irq_save(flags);
busy_wait(delay);
local_irq_restore(flags);
@@ -113,6 +119,14 @@ static int preemptirq_delay_run(void *data)
{
int i;
int s = MIN(burst_size, NR_TEST_FUNCS);
+ struct cpumask cpu_mask;
+
+ if (cpu_affinity > -1) {
+ cpumask_clear(&cpu_mask);
+ cpumask_set_cpu(cpu_affinity, &cpu_mask);
+ if (set_cpus_allowed_ptr(current, &cpu_mask))
+ pr_err("cpu_affinity:%d, failed\n", cpu_affinity);
+ }
for (i = 0; i < s; i++)
(testfuncs[i])(i);
--
2.7.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] kernel: trace: preemptirq_delay_test: add cpu affinity
2021-01-28 1:35 [PATCH] kernel: trace: preemptirq_delay_test: add cpu affinity Song Chen
@ 2021-01-29 22:22 ` Steven Rostedt
0 siblings, 0 replies; 2+ messages in thread
From: Steven Rostedt @ 2021-01-29 22:22 UTC (permalink / raw)
To: Song Chen, Joel Fernandes; +Cc: mingo, linux-kernel, linux-rt-users
Joel,
Can you ack this patch?
-- Steve
On Thu, 28 Jan 2021 09:35:13 +0800
Song Chen <chensong_2000@189.cn> wrote:
> The kernel thread executing test can run on any cpu, which might be
> different cpu latency tracer is running on, as a result, the
> big latency caused by preemptirq delay test can't be detected.
>
> Therefore, the argument cpu_affinity is added to be passed to test,
> ensure it's running on the same cpu with latency tracer.
>
> e.g.
> cyclictest -p 90 -m -c 0 -i 1000 -a 3
> modprobe preemptirq_delay_test test_mode=preempt delay=500 \
> burst_size=3 cpu_affinity=3
>
> Signed-off-by: Song Chen <chensong_2000@189.cn>
> ---
> kernel/trace/Kconfig | 4 ++++
> kernel/trace/preemptirq_delay_test.c | 14 ++++++++++++++
> 2 files changed, 18 insertions(+)
>
> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> index c1a62ae..44dd5c0 100644
> --- a/kernel/trace/Kconfig
> +++ b/kernel/trace/Kconfig
> @@ -886,6 +886,10 @@ config PREEMPTIRQ_DELAY_TEST
> irq-disabled critical sections for 500us:
> modprobe preemptirq_delay_test test_mode=irq delay=500 burst_size=3
>
> + What's more, if you want to attach the test on the cpu which the latency
> + tracer is running on, specify cpu_affinity=cpu_num at the end of the
> + command.
> +
> If unsure, say N
>
> config SYNTH_EVENT_GEN_TEST
> diff --git a/kernel/trace/preemptirq_delay_test.c b/kernel/trace/preemptirq_delay_test.c
> index 312d1a0..8c4ffd0 100644
> --- a/kernel/trace/preemptirq_delay_test.c
> +++ b/kernel/trace/preemptirq_delay_test.c
> @@ -21,13 +21,16 @@
> static ulong delay = 100;
> static char test_mode[12] = "irq";
> static uint burst_size = 1;
> +static int cpu_affinity = -1;
>
> module_param_named(delay, delay, ulong, 0444);
> module_param_string(test_mode, test_mode, 12, 0444);
> module_param_named(burst_size, burst_size, uint, 0444);
> +module_param_named(cpu_affinity, cpu_affinity, int, 0444);
> MODULE_PARM_DESC(delay, "Period in microseconds (100 us default)");
> MODULE_PARM_DESC(test_mode, "Mode of the test such as preempt, irq, or alternate (default irq)");
> MODULE_PARM_DESC(burst_size, "The size of a burst (default 1)");
> +MODULE_PARM_DESC(cpu_affinity, "Cpu num test is running on");
>
> static struct completion done;
>
> @@ -36,7 +39,9 @@ static struct completion done;
> static void busy_wait(ulong time)
> {
> u64 start, end;
> +
> start = trace_clock_local();
> +
> do {
> end = trace_clock_local();
> if (kthread_should_stop())
> @@ -47,6 +52,7 @@ static void busy_wait(ulong time)
> static __always_inline void irqoff_test(void)
> {
> unsigned long flags;
> +
> local_irq_save(flags);
> busy_wait(delay);
> local_irq_restore(flags);
> @@ -113,6 +119,14 @@ static int preemptirq_delay_run(void *data)
> {
> int i;
> int s = MIN(burst_size, NR_TEST_FUNCS);
> + struct cpumask cpu_mask;
> +
> + if (cpu_affinity > -1) {
> + cpumask_clear(&cpu_mask);
> + cpumask_set_cpu(cpu_affinity, &cpu_mask);
> + if (set_cpus_allowed_ptr(current, &cpu_mask))
> + pr_err("cpu_affinity:%d, failed\n", cpu_affinity);
> + }
>
> for (i = 0; i < s; i++)
> (testfuncs[i])(i);
^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-01-28 1:35 [PATCH] kernel: trace: preemptirq_delay_test: add cpu affinity Song Chen
2021-01-29 22:22 ` Steven Rostedt
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