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Date: Mon, 21 Nov 2011 11:22:27 -0500
From: Eric B Munson <emunson@...bm.net>
To: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: mingo@...e.hu, William Cohen <wcohen@...hat.com>,
linux-kernel@...r.kernel.org, Michael Cree <mcree@...on.net.nz>,
Will Deacon <will.deacon@....com>,
Deng-Cheng Zhu <dengcheng.zhu@...il.com>,
Anton Blanchard <anton@...ba.org>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Paul Mundt <lethal@...ux-sh.org>,
"David S. Miller" <davem@...emloft.net>,
Richard Kuo <rkuo@...eaurora.org>,
Stephane Eranian <eranian@...gle.com>,
Arun Sharma <asharma@...com>, Vince Weaver <vince@...ter.net>
Subject: Re: [RFC][PATCH 2/6] perf, arch: Rework perf_event_index()
On Mon, 21 Nov 2011, Peter Zijlstra wrote:
> Put the logic to compute the event index into a per pmu method. This
> is required because the x86 rules are weird and wonderful and don't
> match the capabilities of the current scheme.
>
> AFAIK only powerpc actually has a usable userspace read of the PMCs
> but I'm not at all sure anybody actually used that.
>
> ARM looks like it cared, but I really wouldn't know, Will?
>
> For the rest we preserve the status quo with a default function.
>
> We probably want to provide an explicit method for sw counters and the
> like so they don't try and dereference event->hw.index which is a
> random field in the middle of their hrtimer structure.
>
> Cc: Michael Cree <mcree@...on.net.nz>
> Cc: Will Deacon <will.deacon@....com>
> Cc: Deng-Cheng Zhu <dengcheng.zhu@...il.com>
> Cc: Anton Blanchard <anton@...ba.org>
> Cc: Eric B Munson <emunson@...bm.net>
> Cc: Heiko Carstens <heiko.carstens@...ibm.com>
> Cc: Paul Mundt <lethal@...ux-sh.org>
> Cc: David S. Miller <davem@...emloft.net>
> Cc: Richard Kuo <rkuo@...eaurora.org>
> Cc: Stephane Eranian <eranian@...gle.com>
> Cc: Arun Sharma <asharma@...com>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Acked-by: Eric B Munson <emunson@...bm.net>
> ---
> arch/arm/include/asm/perf_event.h | 4 ----
> arch/arm/kernel/perf_event.c | 10 ++++++++++
> arch/frv/include/asm/perf_event.h | 2 --
> arch/hexagon/include/asm/perf_event.h | 2 --
> arch/powerpc/include/asm/perf_event_server.h | 2 --
> arch/powerpc/kernel/perf_event.c | 6 ++++++
> arch/s390/include/asm/perf_event.h | 1 -
> arch/x86/include/asm/perf_event.h | 2 --
> include/linux/perf_event.h | 6 ++++++
> kernel/events/core.c | 14 +++++++++-----
> 10 files changed, 31 insertions(+), 18 deletions(-)
> Index: linux-2.6/include/linux/perf_event.h
> ===================================================================
> --- linux-2.6.orig/include/linux/perf_event.h
> +++ linux-2.6/include/linux/perf_event.h
> @@ -679,6 +679,12 @@ struct pmu {
> * for each successful ->add() during the transaction.
> */
> void (*cancel_txn) (struct pmu *pmu); /* optional */
> +
> + /*
> + * Will return the value for perf_event_mmap_page::index for this event,
> + * if no implementation is provided it will default to: event->hw.idx + 1.
> + */
> + int (*event_idx) (struct perf_event *event); /*optional */
> };
>
> /**
> Index: linux-2.6/kernel/events/core.c
> ===================================================================
> --- linux-2.6.orig/kernel/events/core.c
> +++ linux-2.6/kernel/events/core.c
> @@ -3191,10 +3191,6 @@ int perf_event_task_disable(void)
> return 0;
> }
>
> -#ifndef PERF_EVENT_INDEX_OFFSET
> -# define PERF_EVENT_INDEX_OFFSET 0
> -#endif
> -
> static int perf_event_index(struct perf_event *event)
> {
> if (event->hw.state & PERF_HES_STOPPED)
> @@ -3203,7 +3199,7 @@ static int perf_event_index(struct perf_
> if (event->state != PERF_EVENT_STATE_ACTIVE)
> return 0;
>
> - return event->hw.idx + 1 - PERF_EVENT_INDEX_OFFSET;
> + return event->pmu->event_idx(event);
> }
>
> static void calc_timer_values(struct perf_event *event,
> @@ -5334,6 +5330,11 @@ static void perf_pmu_cancel_txn(struct p
> perf_pmu_enable(pmu);
> }
>
> +static int perf_event_idx_default(struct perf_event *event)
> +{
> + return event->hw.idx + 1;
> +}
> +
> /*
> * Ensures all contexts with the same task_ctx_nr have the same
> * pmu_cpu_context too.
> @@ -5523,6 +5524,9 @@ int perf_pmu_register(struct pmu *pmu, c
> pmu->pmu_disable = perf_pmu_nop_void;
> }
>
> + if (!pmu->event_idx)
> + pmu->event_idx = perf_event_idx_default;
> +
> list_add_rcu(&pmu->entry, &pmus);
> ret = 0;
> unlock:
> Index: linux-2.6/arch/arm/include/asm/perf_event.h
> ===================================================================
> --- linux-2.6.orig/arch/arm/include/asm/perf_event.h
> +++ linux-2.6/arch/arm/include/asm/perf_event.h
> @@ -12,10 +12,6 @@
> #ifndef __ARM_PERF_EVENT_H__
> #define __ARM_PERF_EVENT_H__
>
> -/* ARM performance counters start from 1 (in the cp15 accesses) so use the
> - * same indexes here for consistency. */
> -#define PERF_EVENT_INDEX_OFFSET 1
> -
> /* ARM perf PMU IDs for use by internal perf clients. */
> enum arm_perf_pmu_ids {
> ARM_PERF_PMU_ID_XSCALE1 = 0,
> Index: linux-2.6/arch/arm/kernel/perf_event.c
> ===================================================================
> --- linux-2.6.orig/arch/arm/kernel/perf_event.c
> +++ linux-2.6/arch/arm/kernel/perf_event.c
> @@ -572,6 +572,15 @@ static void armpmu_disable(struct pmu *p
> armpmu->stop();
> }
>
> +/*
> + * ARM performance counters start from 1 (in the cp15 accesses) so use the
> + * same indexes here for consistency.
> + */
> +static int armpmu_event_idx(struct perf_event *event)
> +{
> + return event->hw.idx;
> +}
> +
> static void __init armpmu_init(struct arm_pmu *armpmu)
> {
> atomic_set(&armpmu->active_events, 0);
> @@ -586,6 +595,7 @@ static void __init armpmu_init(struct ar
> .start = armpmu_start,
> .stop = armpmu_stop,
> .read = armpmu_read,
> + .event_idx = armpmu_event_idx,
> };
> }
>
> Index: linux-2.6/arch/frv/include/asm/perf_event.h
> ===================================================================
> --- linux-2.6.orig/arch/frv/include/asm/perf_event.h
> +++ linux-2.6/arch/frv/include/asm/perf_event.h
> @@ -12,6 +12,4 @@
> #ifndef _ASM_PERF_EVENT_H
> #define _ASM_PERF_EVENT_H
>
> -#define PERF_EVENT_INDEX_OFFSET 0
> -
> #endif /* _ASM_PERF_EVENT_H */
> Index: linux-2.6/arch/hexagon/include/asm/perf_event.h
> ===================================================================
> --- linux-2.6.orig/arch/hexagon/include/asm/perf_event.h
> +++ linux-2.6/arch/hexagon/include/asm/perf_event.h
> @@ -19,6 +19,4 @@
> #ifndef _ASM_PERF_EVENT_H
> #define _ASM_PERF_EVENT_H
>
> -#define PERF_EVENT_INDEX_OFFSET 0
> -
> #endif /* _ASM_PERF_EVENT_H */
> Index: linux-2.6/arch/powerpc/include/asm/perf_event_server.h
> ===================================================================
> --- linux-2.6.orig/arch/powerpc/include/asm/perf_event_server.h
> +++ linux-2.6/arch/powerpc/include/asm/perf_event_server.h
> @@ -61,8 +61,6 @@ struct pt_regs;
> extern unsigned long perf_misc_flags(struct pt_regs *regs);
> extern unsigned long perf_instruction_pointer(struct pt_regs *regs);
>
> -#define PERF_EVENT_INDEX_OFFSET 1
> -
> /*
> * Only override the default definitions in include/linux/perf_event.h
> * if we have hardware PMU support.
> Index: linux-2.6/arch/powerpc/kernel/perf_event.c
> ===================================================================
> --- linux-2.6.orig/arch/powerpc/kernel/perf_event.c
> +++ linux-2.6/arch/powerpc/kernel/perf_event.c
> @@ -1187,6 +1187,11 @@ static int power_pmu_event_init(struct p
> return err;
> }
>
> +static int power_pmu_event_idx(struct perf_event *event)
> +{
> + return event->hw.idx;
> +}
> +
> struct pmu power_pmu = {
> .pmu_enable = power_pmu_enable,
> .pmu_disable = power_pmu_disable,
> @@ -1199,6 +1204,7 @@ struct pmu power_pmu = {
> .start_txn = power_pmu_start_txn,
> .cancel_txn = power_pmu_cancel_txn,
> .commit_txn = power_pmu_commit_txn,
> + .event_idx = power_pmu_event_idx,
> };
>
> /*
> Index: linux-2.6/arch/s390/include/asm/perf_event.h
> ===================================================================
> --- linux-2.6.orig/arch/s390/include/asm/perf_event.h
> +++ linux-2.6/arch/s390/include/asm/perf_event.h
> @@ -6,4 +6,3 @@
>
> /* Empty, just to avoid compiling error */
>
> -#define PERF_EVENT_INDEX_OFFSET 0
> Index: linux-2.6/arch/x86/include/asm/perf_event.h
> ===================================================================
> --- linux-2.6.orig/arch/x86/include/asm/perf_event.h
> +++ linux-2.6/arch/x86/include/asm/perf_event.h
> @@ -187,8 +187,6 @@ extern u32 get_ibs_caps(void);
> #ifdef CONFIG_PERF_EVENTS
> extern void perf_events_lapic_init(void);
>
> -#define PERF_EVENT_INDEX_OFFSET 0
> -
> /*
> * Abuse bit 3 of the cpu eflags register to indicate proper PEBS IP fixups.
> * This flag is otherwise unused and ABI specified to be 0, so nobody should
>
>
> --
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