linux-kernel - Re: [PATCH] cpufreq: stats: Use lock by stat to replace global spin lock

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Message-ID: <20190408053944.wcz2pblevccyftmg@vireshk-i7>
Date:   Mon, 8 Apr 2019 11:09:44 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     Kyle Lin <linkyle0915@...il.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpufreq: stats: Use lock by stat to replace global spin
 lock

On 26-03-19, 11:43, Matthias Kaehlcke wrote:
> On Mon, Mar 25, 2019 at 03:29:33PM +0800, Kyle Lin wrote:
> > Stats is updated by each policy, using the lock by stat can
> > reduce the contention.
> > 
> > Signed-off-by: Kyle Lin <linkyle0915@...il.com>
> > ---
> >  drivers/cpufreq/cpufreq_stats.c | 15 ++++++++-------
> >  1 file changed, 8 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
> > index e2db5581489a..17beb1bc7e16 100644
> > --- a/drivers/cpufreq/cpufreq_stats.c
> > +++ b/drivers/cpufreq/cpufreq_stats.c
> > @@ -14,7 +14,6 @@
> >  #include <linux/module.h>
> >  #include <linux/slab.h>
> >  
> > -static DEFINE_SPINLOCK(cpufreq_stats_lock);
> >  
> >  struct cpufreq_stats {
> >  	unsigned int total_trans;
> > @@ -23,6 +22,7 @@ struct cpufreq_stats {
> >  	unsigned int state_num;
> >  	unsigned int last_index;
> >  	u64 *time_in_state;
> > +	spinlock_t lock;        /*spinlock for stats update*/
> 
> nit: not sure if the comment adds much value. If it stay there it
> needs a blank after '/*' and another before '*/'

Just drop the comment please.

-- 
viresh