From: Jiri Olsa <jolsa@redhat.com>
To: Kan Liang <kan.liang@intel.com>
Cc: a.p.zijlstra@chello.nl, eranian@google.com,
linux-kernel@vger.kernel.org, mingo@redhat.com, paulus@samba.org,
acme@kernel.org, ak@linux.intel.com, "Yan,
Zheng" <zheng.z.yan@intel.com>
Subject: Re: [PATCH V6 13/17] perf, x86: enable LBR callstack when recording callchain
Date: Fri, 24 Oct 2014 15:39:36 +0200 [thread overview]
Message-ID: <20141024133936.GD1036@krava.brq.redhat.com> (raw)
In-Reply-To: <1413755712-8259-14-git-send-email-kan.liang@intel.com>
On Sun, Oct 19, 2014 at 05:55:08PM -0400, Kan Liang wrote:
> Only enable LBR callstack when user requires fp callgraph. The feature
> is not available when PERF_SAMPLE_BRANCH_STACK or PERF_SAMPLE_STACK_USER
> is required.
> Also, this feature only affects how to get user callchain. The kernel
> callchain is always got by frame pointers.
>
> Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
> Signed-off-by: Kan Liang <kan.liang@intel.com>
> ---
> arch/x86/kernel/cpu/perf_event.c | 18 ++++++++++++++++--
> 1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
> index 9656b9e..b3256a3 100644
> --- a/arch/x86/kernel/cpu/perf_event.c
> +++ b/arch/x86/kernel/cpu/perf_event.c
> @@ -424,10 +424,24 @@ int x86_pmu_hw_config(struct perf_event *event)
> if (!event->attr.exclude_kernel)
> *br_type |= PERF_SAMPLE_BRANCH_KERNEL;
> }
> - }
> + } else if (x86_pmu_has_lbr_callstack() &&
> + (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) &&
> + !(event->attr.sample_type & PERF_SAMPLE_STACK_USER) &&
> + !has_branch_stack(event) &&
> + !event->attr.exclude_user &&
> + (event->attach_state & PERF_ATTACH_TASK)) {
> + /*
> + * user did not specify branch_sample_type,
> + * try using the LBR call stack facility to
> + * record call chains of user program.
> + */
> + event->attr.branch_sample_type =
> + PERF_SAMPLE_BRANCH_USER |
> + PERF_SAMPLE_BRANCH_CALL_STACK;
>
I dont see PERF_SAMPLE_BRANCH_CALL_STACK being defind in uapi.. any reason
why I cant enable this feature explicitly?
thanks,
jirka
next prev parent reply other threads:[~2014-10-24 13:39 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-19 21:54 [PATCH V6 00/17] perf, x86: Haswell LBR call stack support Kan Liang
2014-10-19 21:54 ` [PATCH V6 01/17] perf, x86: Reduce lbr_sel_map size Kan Liang
2014-10-24 9:39 ` Peter Zijlstra
2014-11-04 1:07 ` Liang, Kan
2014-11-04 7:14 ` Peter Zijlstra
2014-11-04 7:16 ` Peter Zijlstra
2014-10-19 21:54 ` [PATCH V6 02/17] perf, core: introduce pmu context switch callback Kan Liang
2014-10-19 21:54 ` [PATCH V6 03/17] perf, x86: use context switch callback to flush LBR stack Kan Liang
2014-10-19 21:54 ` [PATCH V6 04/17] perf, x86: Basic Haswell LBR call stack support Kan Liang
2014-10-19 21:55 ` [PATCH V6 05/17] perf, core: pmu specific data for perf task context Kan Liang
2014-10-19 21:55 ` [PATCH V6 06/17] perf, core: always switch pmu specific data during context switch Kan Liang
2014-10-19 21:55 ` [PATCH V6 07/17] perf, x86: allocate space for storing LBR stack Kan Liang
2014-10-19 21:55 ` [PATCH V6 08/17] perf, x86: track number of events that use LBR callstack Kan Liang
2014-10-19 21:55 ` [PATCH V6 09/17] perf, x86: Save/resotre LBR stack during context switch Kan Liang
2014-10-19 21:55 ` [PATCH V6 10/17] perf, core: simplify need branch stack check Kan Liang
2014-10-19 21:55 ` [PATCH V6 11/17] perf, core: expose LBR call stack to user perf tool Kan Liang
2014-10-19 21:55 ` [PATCH V6 12/17] perf, x86: re-organize code that implicitly enables LBR/PEBS Kan Liang
2014-10-19 21:55 ` [PATCH V6 13/17] perf, x86: enable LBR callstack when recording callchain Kan Liang
2014-10-24 13:39 ` Jiri Olsa [this message]
2014-10-24 14:49 ` Liang, Kan
2014-10-19 21:55 ` [PATCH V6 14/17] perf, x86: disable FREEZE_LBRS_ON_PMI when LBR operates in callstack mode Kan Liang
2014-10-19 21:55 ` [PATCH V6 15/17] perf, x86: Discard zero length call entries in LBR call stack Kan Liang
2014-10-19 21:55 ` [PATCH V6 16/17] perf tools: handle LBR call stack data Kan Liang
2014-10-19 21:55 ` [PATCH V6 17/17] perf tools: choose to dump callchain from LBR and FP Kan Liang
2014-10-24 13:36 ` Jiri Olsa
2014-10-24 13:55 ` Jiri Olsa
2014-10-24 15:20 ` Liang, Kan
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