linux-kernel - Re: [PATCH V4 08/16] perf, x86: allocate space for storing LBR stack

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Date:	Mon, 07 Jul 2014 14:36:52 +0800
From:	"Yan, Zheng" <zheng.z.yan@...el.com>
To:	linux-kernel@...r.kernel.org
CC:	a.p.zijlstra@...llo.nl, mingo@...nel.org, acme@...radead.org,
	eranian@...gle.com, andi@...stfloor.org
Subject: Re: [PATCH V4 08/16] perf, x86: allocate space for storing LBR stack

please ignore this patch

On 07/07/2014 02:28 PM, Yan, Zheng wrote:
> When the LBR call stack is enabled, it is necessary to save/restore
> the LBR stack on context switch. We can use pmu specific data to
> store LBR stack when task is scheduled out. This patch adds code
> that allocates the pmu specific data.
> 
> Signed-off-by: Yan, Zheng <zheng.z.yan@...el.com>
> Reviewed-by: Stephane Eranian <eranian@...gle.com>
> ---
>  arch/x86/kernel/cpu/perf_event.c | 1 +
>  arch/x86/kernel/cpu/perf_event.h | 7 +++++++
>  2 files changed, 8 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
> index 8868e9b..2008c2a 100644
> --- a/arch/x86/kernel/cpu/perf_event.c
> +++ b/arch/x86/kernel/cpu/perf_event.c
> @@ -1907,6 +1907,7 @@ static struct pmu pmu = {
>  
>  	.event_idx		= x86_pmu_event_idx,
>  	.sched_task		= x86_pmu_sched_task,
> +	.task_ctx_size          = sizeof(struct x86_perf_task_context),
>  };
>  
>  void arch_perf_update_userpage(struct perf_event_mmap_page *userpg, u64 now)
> diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h
> index cc25819..b0eabca 100644
> --- a/arch/x86/kernel/cpu/perf_event.h
> +++ b/arch/x86/kernel/cpu/perf_event.h
> @@ -472,6 +472,13 @@ struct x86_pmu {
>  	struct perf_guest_switch_msr *(*guest_get_msrs)(int *nr);
>  };
>  
> +struct x86_perf_task_context {
> +	u64 lbr_from[MAX_LBR_ENTRIES];
> +	u64 lbr_to[MAX_LBR_ENTRIES];
> +	int lbr_callstack_users;
> +	int lbr_stack_state;
> +};
> +
>  enum {
>  	PERF_SAMPLE_BRANCH_CALL_STACK_SHIFT = PERF_SAMPLE_BRANCH_MAX_SHIFT,
>  	PERF_SAMPLE_BRANCH_SELECT_MAP_SIZE,
> 

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