From 7f33f9c5cc3c99aeaf4d266a7ed502b828115a53 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Sat, 5 Dec 2009 12:01:17 +0100 Subject: [PATCH] x86/perf: Exclude the debug stack from the callchains Dumping the callchains from breakpoint events with perf gives strange results: 3.75% perf [kernel] [k] _raw_read_unlock | --- _raw_read_unlock perf_callchain perf_prepare_sample __perf_event_overflow perf_swevent_overflow perf_swevent_add perf_bp_event hw_breakpoint_exceptions_notify notifier_call_chain __atomic_notifier_call_chain atomic_notifier_call_chain notify_die do_debug debug munmap We are infected with all the debug stack. Like the nmi stack, the debug stack is undesired as it is part of the profiling path, not helpful for the user. Ignore it. Signed-off-by: Frederic Weisbecker Cc: Peter Zijlstra Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo Cc: "K. Prasad" --- arch/x86/kernel/cpu/perf_event.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index c1bbed1021d9..d35f26076ae5 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -2287,7 +2287,7 @@ void callchain_store(struct perf_callchain_entry *entry, u64 ip) static DEFINE_PER_CPU(struct perf_callchain_entry, pmc_irq_entry); static DEFINE_PER_CPU(struct perf_callchain_entry, pmc_nmi_entry); -static DEFINE_PER_CPU(int, in_nmi_frame); +static DEFINE_PER_CPU(int, in_ignored_frame); static void @@ -2303,8 +2303,9 @@ static void backtrace_warning(void *data, char *msg) static int backtrace_stack(void *data, char *name) { - per_cpu(in_nmi_frame, smp_processor_id()) = - x86_is_stack_id(NMI_STACK, name); + per_cpu(in_ignored_frame, smp_processor_id()) = + x86_is_stack_id(NMI_STACK, name) || + x86_is_stack_id(DEBUG_STACK, name); return 0; } @@ -2313,7 +2314,7 @@ static void backtrace_address(void *data, unsigned long addr, int reliable) { struct perf_callchain_entry *entry = data; - if (per_cpu(in_nmi_frame, smp_processor_id())) + if (per_cpu(in_ignored_frame, smp_processor_id())) return; if (reliable) -- GitLab