linux-kernel - Re: [PATCH] update clocksource raw_time in timekeeping

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Date:	Fri, 11 Sep 2009 11:35:53 +0800
From:	ye janboe <janboe.ye@...il.com>
To:	john stultz <johnstul@...ibm.com>
Cc:	Yong Zhang <yong.zhang0@...il.com>, zippel@...ux-m68k.org,
	akpm@...ux-foundation.org, mingo@...e.hu,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] update clocksource raw_time in timekeeping_suspend

So CLOCK_MONOTONIC_RAW is not suitable for getting real hw time which
includes sleep time.

Is there other timer suitable for this?

Thanks

2009/9/11 john stultz <johnstul@...ibm.com>:
> On Thu, 2009-09-10 at 17:31 +0800, Yong Zhang wrote:
>> On Thu, Sep 10, 2009 at 4:07 PM, ye janboe <janboe.ye@...il.com> wrote:
>> > hi, John
>> >
>> > Thanks for your comments.
>> >
>> > After sent this patch, I realize that this patch exposes the hardware
>> > detail ugly in common code.
>> >
>> > In embed system, user space apps need to have a method to get the
>> > right time which will not be impacted by NTP and suspend.
>> >
>> > Yes, you are right. I want to add sleep_length to the raw time and
>> > user space apps could get the right time after suspend.
>> >
>>
>> What I get from the code is that CLOCK_MONOTONIC doesn't consider
>> sleep_length either. Do I miss something?
>
> You're quite right. I forgot we drop sleep_length from
> wall_to_monotonic, so it should not increase while we're suspended.
>
> Janboe: So I think things are fine as they stand. No patch necessary.
>
> But please let me know if I'm yet again forgetting something or you're
> finding CLOCK_MONOTONIC_RAW to be insufficient in some way.
>
> thanks
> -john
>
>
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