| Message ID | 20180628182149.226164-7-joel@joelfernandes.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
On Thu, 28 Jun 2018 11:21:48 -0700 Joel Fernandes <joel@joelfernandes.org> wrote: > From: "Joel Fernandes (Google)" <joel@joelfernandes.org> > > In this patch we introduce a test module for simulating a long atomic > section in the kernel which the preemptoff or irqsoff tracers can > detect. This module is to be used only for test purposes and is default > disabled. > > Following is the expected output (only briefly shown) that can be parsed > to verify that the tracers are working correctly. We will use this from > the kselftests in future patches. > > For the preemptoff tracer: > > echo preemptoff > /d/tracing/current_tracer > sleep 1 > insmod ./test_atomic_sections.ko atomic_mode=preempt atomic_time=500000 > sleep 1 > bash-4.3# cat /d/tracing/trace > preempt -1066 2...2 0us@: atomic_sect_run <-atomic_sect_run > preempt -1066 2...2 500002us : atomic_sect_run <-atomic_sect_run > preempt -1066 2...2 500004us : tracer_preempt_on <-atomic_sect_run > preempt -1066 2...2 500012us : <stack trace> > => kthread > => ret_from_fork > > For the irqsoff tracer: > > echo irqsoff > /d/tracing/current_tracer > sleep 1 > insmod ./test_atomic_sections.ko atomic_mode=irq atomic_time=500000 > sleep 1 > bash-4.3# cat /d/tracing/trace > irq dis -1069 1d..1 0us@: atomic_sect_run > irq dis -1069 1d..1 500001us : atomic_sect_run > irq dis -1069 1d..1 500002us : tracer_hardirqs_on <-atomic_sect_run > irq dis -1069 1d..1 500005us : <stack trace> > => ret_from_fork > > Co-developed-by: Erick Reyes <erickreyes@google.com> > Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> > --- > lib/Kconfig.debug | 8 ++++ > lib/Makefile | 1 + > lib/test_atomic_sections.c | 77 ++++++++++++++++++++++++++++++++++++++ I think this code should reside in kernel/trace directory. I already have modules there. See the ring_buffer_benchmark code and the test module for mmio tracer. > 3 files changed, 86 insertions(+) > create mode 100644 lib/test_atomic_sections.c > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 8838d1158d19..622c90e1e066 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -1956,6 +1956,14 @@ config TEST_KMOD > > If unsure, say N. > > +config TEST_ATOMIC_SECTIONS > + tristate "Simulate atomic sections for tracers to detect" Hmm, I don't like this title. It's not very obvious to what it is about. What about "Preempt / IRQ disable delay thread to test latency tracers" ? Or something along those lines. > + depends on m > + help > + Select this option to build a test module that can help test atomic > + sections by simulating them with a duration supplied as a module > + parameter. Preempt disable and irq disable modes can be requested. "If unsure say N" > + > config TEST_DEBUG_VIRTUAL > tristate "Test CONFIG_DEBUG_VIRTUAL feature" > depends on DEBUG_VIRTUAL > diff --git a/lib/Makefile b/lib/Makefile > index 90dc5520b784..7831e747bf72 100644 > --- a/lib/Makefile > +++ b/lib/Makefile > @@ -44,6 +44,7 @@ obj-y += string_helpers.o > obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o > obj-y += hexdump.o > obj-$(CONFIG_TEST_HEXDUMP) += test_hexdump.o > +obj-$(CONFIG_TEST_ATOMIC_SECTIONS) += test_atomic_sections.o > obj-y += kstrtox.o > obj-$(CONFIG_FIND_BIT_BENCHMARK) += find_bit_benchmark.o > obj-$(CONFIG_TEST_BPF) += test_bpf.o > diff --git a/lib/test_atomic_sections.c b/lib/test_atomic_sections.c > new file mode 100644 > index 000000000000..1eef518f0974 > --- /dev/null > +++ b/lib/test_atomic_sections.c > @@ -0,0 +1,77 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Atomic section emulation test module > + * > + * Emulates atomic sections by disabling IRQs or preemption > + * and doing a busy wait for a specified amount of time. > + * This can be used for testing of different atomic section > + * tracers such as irqsoff tracers. > + * > + * (c) 2018. Google LLC > + */ > + > +#include <linux/delay.h> > +#include <linux/interrupt.h> > +#include <linux/irq.h> > +#include <linux/kernel.h> > +#include <linux/kthread.h> > +#include <linux/ktime.h> > +#include <linux/module.h> > +#include <linux/printk.h> > +#include <linux/string.h> > + > +static ulong atomic_time = 100; > +static char atomic_mode[10] = "irq"; > + > +module_param_named(atomic_time, atomic_time, ulong, S_IRUGO); > +module_param_string(atomic_mode, atomic_mode, 10, S_IRUGO); > +MODULE_PARM_DESC(atomic_time, "Period in microseconds (100 uS default)"); It's not a "Period", it's a delay. "Length of time in critical section" > +MODULE_PARM_DESC(atomic_mode, "Mode of the test such as preempt or irq (default irq)"); "Mode of the test: preempt or irq disabled (default irq)" > + > +static void busy_wait(ulong time) > +{ > + ktime_t start, end; > + start = ktime_get(); > + do { > + end = ktime_get(); > + if (kthread_should_stop()) > + break; > + } while (ktime_to_ns(ktime_sub(end, start)) < (time * 1000)); > +} > + > +int atomic_sect_run(void *data) > +{ > + unsigned long flags; > + > + if (!strcmp(atomic_mode, "irq")) { > + local_irq_save(flags); > + busy_wait(atomic_time); > + local_irq_restore(flags); > + } else if (!strcmp(atomic_mode, "preempt")) { > + preempt_disable(); > + busy_wait(atomic_time); > + preempt_enable(); > + } So this is a one shot deal? That should be explained somewhere, probably in the config help message. In fact, I think the config help message should show how to use this. -- Steve > + > + return 0; > +} > + > +static int __init atomic_sect_init(void) > +{ > + char task_name[50]; > + struct task_struct *test_task; > + > + snprintf(task_name, sizeof(task_name), "%s_test", atomic_mode); > + > + test_task = kthread_run(atomic_sect_run, NULL, task_name); > + return PTR_ERR_OR_ZERO(test_task); > +} > + > +static void __exit atomic_sect_exit(void) > +{ > + return; > +} > + > +module_init(atomic_sect_init) > +module_exit(atomic_sect_exit) > +MODULE_LICENSE("GPL v2"); -- To unsubscribe from this list: send the line "unsubscribe linux-kselftest" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jul 10, 2018 at 08:47:07PM -0400, Steven Rostedt wrote: > On Thu, 28 Jun 2018 11:21:48 -0700 > Joel Fernandes <joel@joelfernandes.org> wrote: > > > From: "Joel Fernandes (Google)" <joel@joelfernandes.org> > > > > In this patch we introduce a test module for simulating a long atomic > > section in the kernel which the preemptoff or irqsoff tracers can > > detect. This module is to be used only for test purposes and is default > > disabled. > > > > Following is the expected output (only briefly shown) that can be parsed > > to verify that the tracers are working correctly. We will use this from > > the kselftests in future patches. > > > > For the preemptoff tracer: > > > > echo preemptoff > /d/tracing/current_tracer > > sleep 1 > > insmod ./test_atomic_sections.ko atomic_mode=preempt atomic_time=500000 > > sleep 1 > > bash-4.3# cat /d/tracing/trace > > preempt -1066 2...2 0us@: atomic_sect_run <-atomic_sect_run > > preempt -1066 2...2 500002us : atomic_sect_run <-atomic_sect_run > > preempt -1066 2...2 500004us : tracer_preempt_on <-atomic_sect_run > > preempt -1066 2...2 500012us : <stack trace> > > => kthread > > => ret_from_fork > > > > For the irqsoff tracer: > > > > echo irqsoff > /d/tracing/current_tracer > > sleep 1 > > insmod ./test_atomic_sections.ko atomic_mode=irq atomic_time=500000 > > sleep 1 > > bash-4.3# cat /d/tracing/trace > > irq dis -1069 1d..1 0us@: atomic_sect_run > > irq dis -1069 1d..1 500001us : atomic_sect_run > > irq dis -1069 1d..1 500002us : tracer_hardirqs_on <-atomic_sect_run > > irq dis -1069 1d..1 500005us : <stack trace> > > => ret_from_fork > > > > Co-developed-by: Erick Reyes <erickreyes@google.com> > > Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > > Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> > > --- > > lib/Kconfig.debug | 8 ++++ > > lib/Makefile | 1 + > > lib/test_atomic_sections.c | 77 ++++++++++++++++++++++++++++++++++++++ > > I think this code should reside in kernel/trace directory. I already > have modules there. See the ring_buffer_benchmark code and the test > module for mmio tracer. Ok, I'll move it to there. > > 3 files changed, 86 insertions(+) > > create mode 100644 lib/test_atomic_sections.c > > > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > > index 8838d1158d19..622c90e1e066 100644 > > --- a/lib/Kconfig.debug > > +++ b/lib/Kconfig.debug > > @@ -1956,6 +1956,14 @@ config TEST_KMOD > > > > If unsure, say N. > > > > +config TEST_ATOMIC_SECTIONS > > + tristate "Simulate atomic sections for tracers to detect" > > Hmm, I don't like this title. It's not very obvious to what it is > about. What about "Preempt / IRQ disable delay thread to test latency > tracers" ? Or something along those lines. Sure, I'll change it to that. I agree its better. I'll change the text to that and call the config TEST_PREEMPT_IRQ_DISABLE_DELAY. > > + depends on m > > + help > > + Select this option to build a test module that can help test atomic > > + sections by simulating them with a duration supplied as a module > > + parameter. Preempt disable and irq disable modes can be requested. > > "If unsure say N" Sure, sounds good. > > + > > config TEST_DEBUG_VIRTUAL > > tristate "Test CONFIG_DEBUG_VIRTUAL feature" > > depends on DEBUG_VIRTUAL > > diff --git a/lib/Makefile b/lib/Makefile > > index 90dc5520b784..7831e747bf72 100644 > > --- a/lib/Makefile > > +++ b/lib/Makefile > > @@ -44,6 +44,7 @@ obj-y += string_helpers.o > > obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o > > obj-y += hexdump.o > > obj-$(CONFIG_TEST_HEXDUMP) += test_hexdump.o > > +obj-$(CONFIG_TEST_ATOMIC_SECTIONS) += test_atomic_sections.o > > obj-y += kstrtox.o > > obj-$(CONFIG_FIND_BIT_BENCHMARK) += find_bit_benchmark.o > > obj-$(CONFIG_TEST_BPF) += test_bpf.o > > diff --git a/lib/test_atomic_sections.c b/lib/test_atomic_sections.c > > new file mode 100644 > > index 000000000000..1eef518f0974 > > --- /dev/null > > +++ b/lib/test_atomic_sections.c > > @@ -0,0 +1,77 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * Atomic section emulation test module > > + * > > + * Emulates atomic sections by disabling IRQs or preemption > > + * and doing a busy wait for a specified amount of time. > > + * This can be used for testing of different atomic section > > + * tracers such as irqsoff tracers. > > + * > > + * (c) 2018. Google LLC > > + */ > > + > > +#include <linux/delay.h> > > +#include <linux/interrupt.h> > > +#include <linux/irq.h> > > +#include <linux/kernel.h> > > +#include <linux/kthread.h> > > +#include <linux/ktime.h> > > +#include <linux/module.h> > > +#include <linux/printk.h> > > +#include <linux/string.h> > > + > > +static ulong atomic_time = 100; > > +static char atomic_mode[10] = "irq"; > > + > > +module_param_named(atomic_time, atomic_time, ulong, S_IRUGO); > > +module_param_string(atomic_mode, atomic_mode, 10, S_IRUGO); > > +MODULE_PARM_DESC(atomic_time, "Period in microseconds (100 uS default)"); > > It's not a "Period", it's a delay. "Length of time in critical section" Sure. > > +MODULE_PARM_DESC(atomic_mode, "Mode of the test such as preempt or irq (default irq)"); > > "Mode of the test: preempt or irq disabled (default irq)" Ok. > > + > > +static void busy_wait(ulong time) > > +{ > > + ktime_t start, end; > > + start = ktime_get(); > > + do { > > + end = ktime_get(); > > + if (kthread_should_stop()) > > + break; > > + } while (ktime_to_ns(ktime_sub(end, start)) < (time * 1000)); > > +} > > + > > +int atomic_sect_run(void *data) > > +{ > > + unsigned long flags; > > + > > + if (!strcmp(atomic_mode, "irq")) { > > + local_irq_save(flags); > > + busy_wait(atomic_time); > > + local_irq_restore(flags); > > + } else if (!strcmp(atomic_mode, "preempt")) { > > + preempt_disable(); > > + busy_wait(atomic_time); > > + preempt_enable(); > > + } > > So this is a one shot deal? That should be explained somewhere, > probably in the config help message. In fact, I think the config help > message should show how to use this. Sounds good, I'll clarify it better. Thanks! - Joel -- To unsubscribe from this list: send the line "unsubscribe linux-kselftest" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 8838d1158d19..622c90e1e066 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1956,6 +1956,14 @@ config TEST_KMOD If unsure, say N. +config TEST_ATOMIC_SECTIONS + tristate "Simulate atomic sections for tracers to detect" + depends on m + help + Select this option to build a test module that can help test atomic + sections by simulating them with a duration supplied as a module + parameter. Preempt disable and irq disable modes can be requested. + config TEST_DEBUG_VIRTUAL tristate "Test CONFIG_DEBUG_VIRTUAL feature" depends on DEBUG_VIRTUAL diff --git a/lib/Makefile b/lib/Makefile index 90dc5520b784..7831e747bf72 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -44,6 +44,7 @@ obj-y += string_helpers.o obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o obj-y += hexdump.o obj-$(CONFIG_TEST_HEXDUMP) += test_hexdump.o +obj-$(CONFIG_TEST_ATOMIC_SECTIONS) += test_atomic_sections.o obj-y += kstrtox.o obj-$(CONFIG_FIND_BIT_BENCHMARK) += find_bit_benchmark.o obj-$(CONFIG_TEST_BPF) += test_bpf.o diff --git a/lib/test_atomic_sections.c b/lib/test_atomic_sections.c new file mode 100644 index 000000000000..1eef518f0974 --- /dev/null +++ b/lib/test_atomic_sections.c @@ -0,0 +1,77 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Atomic section emulation test module + * + * Emulates atomic sections by disabling IRQs or preemption + * and doing a busy wait for a specified amount of time. + * This can be used for testing of different atomic section + * tracers such as irqsoff tracers. + * + * (c) 2018. Google LLC + */ + +#include <linux/delay.h> +#include <linux/interrupt.h> +#include <linux/irq.h> +#include <linux/kernel.h> +#include <linux/kthread.h> +#include <linux/ktime.h> +#include <linux/module.h> +#include <linux/printk.h> +#include <linux/string.h> + +static ulong atomic_time = 100; +static char atomic_mode[10] = "irq"; + +module_param_named(atomic_time, atomic_time, ulong, S_IRUGO); +module_param_string(atomic_mode, atomic_mode, 10, S_IRUGO); +MODULE_PARM_DESC(atomic_time, "Period in microseconds (100 uS default)"); +MODULE_PARM_DESC(atomic_mode, "Mode of the test such as preempt or irq (default irq)"); + +static void busy_wait(ulong time) +{ + ktime_t start, end; + start = ktime_get(); + do { + end = ktime_get(); + if (kthread_should_stop()) + break; + } while (ktime_to_ns(ktime_sub(end, start)) < (time * 1000)); +} + +int atomic_sect_run(void *data) +{ + unsigned long flags; + + if (!strcmp(atomic_mode, "irq")) { + local_irq_save(flags); + busy_wait(atomic_time); + local_irq_restore(flags); + } else if (!strcmp(atomic_mode, "preempt")) { + preempt_disable(); + busy_wait(atomic_time); + preempt_enable(); + } + + return 0; +} + +static int __init atomic_sect_init(void) +{ + char task_name[50]; + struct task_struct *test_task; + + snprintf(task_name, sizeof(task_name), "%s_test", atomic_mode); + + test_task = kthread_run(atomic_sect_run, NULL, task_name); + return PTR_ERR_OR_ZERO(test_task); +} + +static void __exit atomic_sect_exit(void) +{ + return; +} + +module_init(atomic_sect_init) +module_exit(atomic_sect_exit) +MODULE_LICENSE("GPL v2");