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authorFrederic Weisbecker <fweisbec@gmail.com>2009-07-01 21:02:09 +0200
committerIngo Molnar <mingo@elte.hu>2009-07-01 22:37:23 +0200
commit0406ca6d8e849d9dd027c8cb6791448e81411aef (patch)
tree3de38f9c75f41ec28b5b15b211f4e6df7ea7f437
parent5da50258584469ddfee6545feb4eb2252a8d7e7b (diff)
downloadblackbird-op-linux-0406ca6d8e849d9dd027c8cb6791448e81411aef.tar.gz
blackbird-op-linux-0406ca6d8e849d9dd027c8cb6791448e81411aef.zip
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 <fweisbec@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul Mackerras <paulus@samba.org> Cc: Anton Blanchard <anton@samba.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> LKML-Reference: <1246474930-6088-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--arch/x86/include/asm/stacktrace.h2
-rw-r--r--arch/x86/kernel/cpu/perf_counter.c8
-rw-r--r--arch/x86/kernel/dumpstack_32.c6
-rw-r--r--arch/x86/kernel/dumpstack_64.c22
4 files changed, 30 insertions, 8 deletions
diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h
index f517944b2b17..cf86a5e73815 100644
--- a/arch/x86/include/asm/stacktrace.h
+++ b/arch/x86/include/asm/stacktrace.h
@@ -3,6 +3,8 @@
extern int kstack_depth_to_print;
+int x86_is_stack_id(int id, char *name);
+
/* Generic stack tracer with callbacks */
struct stacktrace_ops {
diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index d4cf4ce19aac..36c3dc7b8991 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);
}
diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index d593cd1f58dc..bca5fba91c9e 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -19,6 +19,12 @@
#include "dumpstack.h"
+/* Just a stub for now */
+int x86_is_stack_id(int id, char *name)
+{
+ return 0;
+}
+
void dump_trace(struct task_struct *task, struct pt_regs *regs,
unsigned long *stack, unsigned long bp,
const struct stacktrace_ops *ops, void *data)
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index d35db5993fd6..54b0a3276766 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -19,10 +19,8 @@
#include "dumpstack.h"
-static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
- unsigned *usedp, char **idp)
-{
- static char ids[][8] = {
+
+static char x86_stack_ids[][8] = {
[DEBUG_STACK - 1] = "#DB",
[NMI_STACK - 1] = "NMI",
[DOUBLEFAULT_STACK - 1] = "#DF",
@@ -33,6 +31,15 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
N_EXCEPTION_STACKS + DEBUG_STKSZ / EXCEPTION_STKSZ - 2] = "#DB[?]"
#endif
};
+
+int x86_is_stack_id(int id, char *name)
+{
+ return x86_stack_ids[id - 1] == name;
+}
+
+static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
+ unsigned *usedp, char **idp)
+{
unsigned k;
/*
@@ -61,7 +68,7 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
if (*usedp & (1U << k))
break;
*usedp |= 1U << k;
- *idp = ids[k];
+ *idp = x86_stack_ids[k];
return (unsigned long *)end;
}
/*
@@ -81,12 +88,13 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
do {
++j;
end -= EXCEPTION_STKSZ;
- ids[j][4] = '1' + (j - N_EXCEPTION_STACKS);
+ x86_stack_ids[j][4] = '1' +
+ (j - N_EXCEPTION_STACKS);
} while (stack < end - EXCEPTION_STKSZ);
if (*usedp & (1U << j))
break;
*usedp |= 1U << j;
- *idp = ids[j];
+ *idp = x86_stack_ids[j];
return (unsigned long *)end;
}
#endif
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