linux-kernel - Re: [PATCH 5/7] perf: Optimise topology iteration

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Date:	Tue, 04 Jan 2011 13:06:16 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Lin Ming <ming.m.lin@...el.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Andi Kleen <andi@...stfloor.org>,
	Stephane Eranian <eranian@...gle.com>, robert.richter@....com,
	lkml <linux-kernel@...r.kernel.org>,
	Borislav Petkov <bp@...64.org>
Subject: Re: [PATCH 5/7] perf: Optimise topology iteration

On Mon, 2010-12-27 at 23:38 +0800, Lin Ming wrote:
> Currently we iterate the full machine looking for a matching core_id/nb
> for the percore and the amd northbridge stuff , using a smaller topology
> mask makes sense. 
> 
> Signed-off-by: Lin Ming <ming.m.lin@...el.com>
> ---
>  arch/x86/kernel/cpu/perf_event_amd.c   |    2 +-
>  arch/x86/kernel/cpu/perf_event_intel.c |    2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/perf_event_amd.c b/arch/x86/kernel/cpu/perf_event_amd.c
> index 67e2202..5a3b7b8 100644
> --- a/arch/x86/kernel/cpu/perf_event_amd.c
> +++ b/arch/x86/kernel/cpu/perf_event_amd.c
> @@ -323,7 +323,7 @@ static void amd_pmu_cpu_starting(int cpu)
>  	nb_id = amd_get_nb_id(cpu);
>  	WARN_ON_ONCE(nb_id == BAD_APICID);
>  
> -	for_each_online_cpu(i) {
> +	for_each_cpu(i, topology_core_cpumask(cpu)) {
>  		nb = per_cpu(cpu_hw_events, i).amd_nb;
>  		if (WARN_ON_ONCE(!nb))
>  			continue;

Borislav, is topology_core_cpumask() the right mask for northbridge_id
span? I could imagine Magny-Cours would have all 12 cores in the
core_cpumask() and have the node_mask() be half that.



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