From 0406ca6d8e849d9dd027c8cb6791448e81411aef Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 1 Jul 2009 21:02:09 +0200 Subject: perf_counter: Ignore the nmi call frames in the x86-64 backtraces About every callchains recorded with perf record are filled up including the internal perfcounter nmi frame: perf_callchain perf_counter_overflow intel_pmu_handle_irq perf_counter_nmi_handler notifier_call_chain atomic_notifier_call_chain notify_die do_nmi nmi We want ignore this frame as it's not interesting for instrumentation. To solve this, we simply ignore every frames from nmi context. New example of "perf report -s sym -c" after this patch: 9.59% [k] search_by_key 4.88% search_by_key reiserfs_read_locked_inode reiserfs_iget reiserfs_lookup do_lookup __link_path_walk path_walk do_path_lookup user_path_at vfs_fstatat vfs_lstat sys_newlstat system_call_fastpath __lxstat 0x406fb1 3.19% search_by_key search_by_entry_key reiserfs_find_entry reiserfs_lookup do_lookup __link_path_walk path_walk do_path_lookup user_path_at vfs_fstatat vfs_lstat sys_newlstat system_call_fastpath __lxstat 0x406fb1 [...] For now this patch only solves the problem in x86-64. Signed-off-by: Frederic Weisbecker Cc: Peter Zijlstra Cc: Mike Galbraith Cc: Paul Mackerras Cc: Anton Blanchard Cc: Arnaldo Carvalho de Melo LKML-Reference: <1246474930-6088-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_counter.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'arch/x86/kernel/cpu') diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index d4cf4ce19aa..36c3dc7b899 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -1561,6 +1561,7 @@ void callchain_store(struct perf_callchain_entry *entry, u64 ip) static DEFINE_PER_CPU(struct perf_callchain_entry, irq_entry); static DEFINE_PER_CPU(struct perf_callchain_entry, nmi_entry); +static DEFINE_PER_CPU(int, in_nmi_frame); static void @@ -1576,7 +1577,9 @@ static void backtrace_warning(void *data, char *msg) static int backtrace_stack(void *data, char *name) { - /* Process all stacks: */ + per_cpu(in_nmi_frame, smp_processor_id()) = + x86_is_stack_id(NMI_STACK, name); + return 0; } @@ -1584,6 +1587,9 @@ 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())) + return; + if (reliable) callchain_store(entry, addr); } -- cgit v1.2.3