| Message ID | 1611797713-20965-1-git-send-email-chensong_2000@189.cn |
|---|---|
| State | New |
| Headers | show |
| Series | kernel: trace: preemptirq_delay_test: add cpu affinity | expand |
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);
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);
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(+)