netdev - Re: [PATCH v8 5/8] time: Add history to cross timestamp interface supporting slower devices

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Message-ID: <CALAqxLVAJDK7fSPpCVQYjZfnZDbJ+NT53zPE0uCy_kuwcoNh4w@mail.gmail.com>
Date:	Wed, 24 Feb 2016 15:07:36 -0800
From:	John Stultz <john.stultz@...aro.org>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	"Christopher S. Hall" <christopher.s.hall@...el.com>,
	Richard Cochran <richardcochran@...il.com>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
	"x86@...nel.org" <x86@...nel.org>,
	lkml <linux-kernel@...r.kernel.org>,
	intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
	"Stanton, Kevin B" <kevin.b.stanton@...el.com>,
	kevin.j.clarke@...el.com
Subject: Re: [PATCH v8 5/8] time: Add history to cross timestamp interface
 supporting slower devices

On Wed, Feb 24, 2016 at 2:56 AM, Thomas Gleixner <tglx@...utronix.de> wrote:
> On Mon, 22 Feb 2016, Christopher S. Hall wrote:
>> +{
>> +     struct timekeeper *tk = &tk_core.timekeeper;
>> +     bool interp_forward;
>> +     u64 corr_raw, corr_real;
>> +     int ret;
>
> Once more:
>
>         struct timekeeper *tk = &tk_core.timekeeper;
>         u64 corr_raw, corr_real;
>         bool interp_forward;
>         int ret;
>
> Is way simpler to parse fast.

So I just went through and addressed these formatting issues in my tree.

but....

>> @@ -929,6 +1046,12 @@ int get_device_system_crosststamp(int (*get_time_fn)
>>       ktime_t base_real;
>>       s64 nsec_raw;
>>       s64 nsec_real;
>> +     cycles_t cycles;
>> +     cycle_t now;

I just noticed this train-wreck: cycles_t and cycle_t are obnoxiously
different types. (One is an int on some arches and the other is a
u64).

You very much want to use cycle_t here. And I think that goes for the
introduced cycle_between() function.

So I'm fixing that up as well in this patch, but there's a few other
spots in this series too.

Sigh. Going to have to find some time to go through and try to zap
cycles_t in the kernel  because having both is just asking for
trouble.  :P

thanks
-john