From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755675AbZGATCU (ORCPT ); Wed, 1 Jul 2009 15:02:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753839AbZGATCN (ORCPT ); Wed, 1 Jul 2009 15:02:13 -0400 Received: from mail-ew0-f210.google.com ([209.85.219.210]:58810 "EHLO mail-ew0-f210.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752834AbZGATCM (ORCPT ); Wed, 1 Jul 2009 15:02:12 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer; b=FTRtsaMaIxHIX4mQtK4aRz9KjdXaJH4G05KZjKvZv6MKpfugKYlgemJcMm1ZzoYPXd Tq725mb5ybf8RbttPk0PGda6E9UYvLJggLi7uCWA5MruyQjW4oxaxtfQWV9lInnQjLTO SJXmfuPNiid2xOWYxlhn7Sui7lhn7fkiRNeyw= From: Frederic Weisbecker To: Ingo Molnar Cc: LKML , Peter Zijlstra , Mike Galbraith , Paul Mackerras , Anton Blanchard , Arnaldo Carvalho de Melo , Frederic Weisbecker Subject: [PATCH 1/2] perfcounter: Ignore the nmi call frames in the x86-64 backtraces Date: Wed, 1 Jul 2009 21:02:09 +0200 Message-Id: <1246474930-6088-1-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.6.2.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- arch/x86/include/asm/stacktrace.h | 2 ++ arch/x86/kernel/cpu/perf_counter.c | 8 +++++++- arch/x86/kernel/dumpstack_32.c | 6 ++++++ arch/x86/kernel/dumpstack_64.c | 22 +++++++++++++++------- 4 files changed, 30 insertions(+), 8 deletions(-) diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h index f517944..cf86a5e 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 d4cf4ce..36c3dc7 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 d593cd1..bca5fba 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 d35db59..54b0a32 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 -- 1.6.2.3