linux-kernel - Re: [RFC perf,x86] P4 PMU early draft

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Date:	Wed, 10 Feb 2010 11:12:12 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Cyrill Gorcunov <gorcunov@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Stephane Eranian <eranian@...gle.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Don Zickus <dzickus@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC perf,x86] P4 PMU early draft

On Wed, 2010-02-10 at 01:39 +0300, Cyrill Gorcunov wrote:


> Index: linux-2.6.git/arch/x86/kernel/cpu/perf_event.c
> =====================================================================
> --- linux-2.6.git.orig/arch/x86/kernel/cpu/perf_event.c
> +++ linux-2.6.git/arch/x86/kernel/cpu/perf_event.c
> @@ -26,6 +26,7 @@
>  #include <linux/bitops.h>
>  
>  #include <asm/apic.h>
> +#include <asm/perf_p4.h>
>  #include <asm/stacktrace.h>
>  #include <asm/nmi.h>
>  
> @@ -140,6 +141,7 @@ struct x86_pmu {
>  	u64		max_period;
>  	u64		intel_ctrl;
>  	int		(*hw_config)(struct perf_event_attr *attr, struct hw_perf_event *hwc);
> +	int		(*schedule_events)(struct cpu_hw_events *cpuc, int n, int *assign, int cpu);
>  	void		(*enable_bts)(u64 config);
>  	void		(*disable_bts)(void);
>  

> +/*
> + * This is the most important routine of Netburst PMU actually
> + * and need a huge speedup!
> + */
> +static int p4_pmu_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign, int cpu)
> +{

> +}


> -static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
> +/* we don't use cpu argument here at all */
> +static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign, int cpu)
>  {
>  	struct event_constraint *c, *constraints[X86_PMC_IDX_MAX];
>  	unsigned long used_mask[BITS_TO_LONGS(X86_PMC_IDX_MAX)];


> @@ -1796,7 +2305,7 @@ static int x86_pmu_enable(struct perf_ev
>  	if (n < 0)
>  		return n;
>  
> -	ret = x86_schedule_events(cpuc, n, assign);
> +	ret = x86_pmu.schedule_events(cpuc, n, assign, 0);
>  	if (ret)
>  		return ret;
>  	/*

This look like a bug, surely we can run on !cpu0.

> @@ -2313,7 +2822,7 @@ int hw_perf_group_sched_in(struct perf_e
>  	if (n0 < 0)
>  		return n0;
>  
> -	ret = x86_schedule_events(cpuc, n0, assign);
> +	ret = x86_pmu.schedule_events(cpuc, n0, assign, cpu);
>  	if (ret)
>  		return ret;
>  

I'd try BUG_ON(cpu != smp_processor_id()) and scrap passing that cpu
thing around.

> @@ -2700,6 +3232,7 @@ static int validate_group(struct perf_ev
>  {
>  	struct perf_event *leader = event->group_leader;
>  	struct cpu_hw_events *fake_cpuc;
> +	int cpu = smp_processor_id();
>  	int ret, n;
>  
>  	ret = -ENOMEM;
> @@ -2725,7 +3258,7 @@ static int validate_group(struct perf_ev
>  
>  	fake_cpuc->n_events = n;
>  
> -	ret = x86_schedule_events(fake_cpuc, n, NULL);
> +	ret = x86_pmu.schedule_events(fake_cpuc, n, NULL, cpu);
>  
>  out_free:
>  	kfree(fake_cpuc);


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