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Date: Wed, 13 Jan 2016 08:21:13 -0800
From: Jacob Pan <jacob.jun.pan@linux.intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>, Linux PM <linux-pm@vger.kernel.org>,
        Rafael Wysocki <rafael.j.wysocki@intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        X86 Kernel <x86@kernel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>, jacob.jun.pan@linux.intel.com,
        Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH v2 2/2] powercap/rapl: reduce ipi calls
Message-ID: <20160113082113.3314fa92@icelake>
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On Wed, 13 Jan 2016 10:47:26 +0100 (CET)
Thomas Gleixner <tglx@linutronix.de> wrote:

> So here you actually use that new (misnomed) function, but for 
> 
> > +static void power_limit_irq_save_cpu(void *info)  
> 
> and
> 
> > +static void power_limit_irq_restore_cpu(void *info)  
> 
> you use a bog standard smp function call. What's the benefit of
> adding that rmw function over a bog standard smp function call if you
> can only use it for one instance of the same pattern?
> 
> Boris asked you the same question here
> 
>       https://lkml.kernel.org/r/20151220152749.GA29805@pd.tnic
> 
> but you decided to ignore it.
+Borislav,

Thanks for bring this out. I didn't mean to ignore. I thought my point
was stated in the commit message there was no point of going back and
forth. Read-Modify-Write is quite common, not just for RAPL could be
used by future code. Sorry if I wasn't clear.

Jacob