Following the feedback after the first approach: https://lkml.kernel.org/r/[email protected]
This patch introduces generic SMP function call trace points: - smp:function_call_issue (captures target cpumask and function pointer) - smp:function_call_execute (captures executing cpu and function pointer) Events show function symbols instead of pointers when printk()-ed Signed-off-by: Wojciech Kudla <[email protected]> --- include/trace/events/smp.h | 67 ++++++++++++++++++++++++++++++++++++++ kernel/smp.c | 18 +++++++++- 2 files changed, 84 insertions(+), 1 deletion(-) create mode 100644 include/trace/events/smp.h diff --git a/include/trace/events/smp.h b/include/trace/events/smp.h new file mode 100644 index 000000000000..ecbd2bb7613b --- /dev/null +++ b/include/trace/events/smp.h @@ -0,0 +1,67 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM smp + +#if !defined(_TRACE_SMP_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_SMP_H + +#include <linux/tracepoint.h> + +/** + * function_call_issue - called when an smp call is made + * + * @mask: mask of recipient CPUs for the SMP function call + * @function: pointer to the function to be executed + * + */ +TRACE_EVENT(function_call_issue, + + TP_PROTO(const struct cpumask *mask, smp_call_func_t func), + + TP_ARGS(mask, func), + + TP_STRUCT__entry( + __bitmask(target_cpus, nr_cpumask_bits) + __field(smp_call_func_t, func) + ), + + TP_fast_assign( + __assign_bitmask(target_cpus, cpumask_bits(mask), nr_cpumask_bits); + __entry->func = func; + ), + + TP_printk("target_mask=%s, function=%pS", + __get_bitmask(target_cpus), __entry->func) +); + + +/** + * function_call_execute - called when smp call is executed on the target cpu + * + * @cpu: cpu the SMP function call is being executed on + * @function: pointer to the function to be executed + * + */ +TRACE_EVENT(function_call_execute, + + TP_PROTO(int cpu, smp_call_func_t func), + + TP_ARGS(cpu, func), + + TP_STRUCT__entry( + __field(int, cpu) + __field(smp_call_func_t, func) + ), + + TP_fast_assign( + __entry->cpu = cpu; + __entry->func = func; + ), + + TP_printk("cpu=%d, function=%pS", __entry->cpu, __entry->func) +); + +#endif /* _TRACE_SMP_H */ + +/* This part must be outside protection */ +#include <trace/define_trace.h> diff --git a/kernel/smp.c b/kernel/smp.c index 7dbcb402c2fc..acb20bd118e0 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -21,6 +21,9 @@ #include <linux/sched/idle.h> #include <linux/hypervisor.h> +#define CREATE_TRACE_POINTS +#include <trace/events/smp.h> + #include "smpboot.h" enum { @@ -176,8 +179,12 @@ static int generic_exec_single(int cpu, call_single_data_t *csd, * locking and barrier primitives. Generic code isn't really * equipped to do the right thing... */ - if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu))) + if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu))) { + if (trace_function_call_issue_enabled()) + trace_function_call_issue(cpumask_of(cpu), func); + arch_send_call_function_single_ipi(cpu); + } return 0; } @@ -241,10 +248,17 @@ static void flush_smp_call_function_queue(bool warn_cpu_offline) /* Do we wait until *after* callback? */ if (csd->flags & CSD_FLAG_SYNCHRONOUS) { + if (trace_function_call_execute_enabled()) + trace_function_call_execute(smp_processor_id(), func); + func(info); csd_unlock(csd); } else { csd_unlock(csd); + + if (trace_function_call_execute_enabled()) + trace_function_call_execute(smp_processor_id(), func); + func(info); } } @@ -474,6 +488,8 @@ void smp_call_function_many(const struct cpumask *mask, __cpumask_set_cpu(cpu, cfd->cpumask_ipi); } + trace_function_call_issue(cfd->cpumask_ipi, func); + /* Send a message to all CPUs in the map */ arch_send_call_function_ipi_mask(cfd->cpumask_ipi); -- 2.17.1
