linux-kernel - Re: [PATCH] arm64: topology: Drop the useless update to per-cpu cycles

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Date:   Fri, 11 Dec 2020 12:18:50 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Ionela Voinescu <ionela.voinescu@....com>
Cc:     Vincent Guittot <vincent.guittot@...aro.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: topology: Drop the useless update to per-cpu
 cycles

On 10-12-20, 11:17, Viresh Kumar wrote:
> The previous call to update_freq_counters_refs() has already updated the
> per-cpu variables, don't overwrite them with the same value again.
> 
> Fixes: 4b9cf23c179a ("arm64: wrap and generalise counter read functions")
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
>  arch/arm64/kernel/topology.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
> index c8308befdb1e..f6faa697e83e 100644
> --- a/arch/arm64/kernel/topology.c
> +++ b/arch/arm64/kernel/topology.c
> @@ -314,7 +314,7 @@ void topology_scale_freq_tick(void)
>  
>  	if (unlikely(core_cnt <= prev_core_cnt ||
>  		     const_cnt <= prev_const_cnt))
> -		goto store_and_exit;
> +		return;
>  
>  	/*
>  	 *	    /\core    arch_max_freq_scale
> @@ -331,10 +331,6 @@ void topology_scale_freq_tick(void)
>  
>  	scale = min_t(unsigned long, scale, SCHED_CAPACITY_SCALE);
>  	this_cpu_write(freq_scale, (unsigned long)scale);
> -
> -store_and_exit:
> -	this_cpu_write(arch_core_cycles_prev, core_cnt);
> -	this_cpu_write(arch_const_cycles_prev, const_cnt);
>  }
>  
>  #ifdef CONFIG_ACPI_CPPC_LIB

Catalin: Can you please pick this up for 5.11-rc1, the earlier patch
(from fixes) is already in your tree. Thanks.

-- 
viresh