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From: john stultz <johnstul-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
To: Alexander Shishkin <virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>
Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>,
	Alexander Viro
	<viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>,
	Greg Kroah-Hartman <gregkh-l3A5Bk7waGM@public.gmane.org>,
	Feng Tang <feng.tang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	Michael Tokarev <mjt-XAri/EZa3C4vJsYlp49lxw@public.gmane.org>,
	Marcelo Tosatti
	<mtosatti-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Chris Friesen
	<chris.friesen-b7o/lNNmKxtBDgjK7y7TUQ@public.gmane.org>,
	Kay Sievers <kay.sievers-tD+1rO4QERM@public.gmane.org>,
	"Kirill A. Shutemov"
	<kirill-oKw7cIdHH8eLwutG50LtGA@public.gmane.org>,
	Artem Bityutskiy
	<dedekind1-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Davide Libenzi <davidel-AhlLAIvw+VEjIGhXcJzhZg@public.gmane.org>,
	Lennart Poettering
	<mzxreary-uLTowLwuiw4b1SvskN2V4Q@public.gmane.org>,
	linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] timerfd: add TFD_NOTIFY_CLOCK_SET to watch for clock changes
Date: Wed, 01 Dec 2010 16:14:27 -0800	[thread overview]
Message-ID: <1291248867.2846.37.camel@work-vm> (raw)
In-Reply-To: <1291167587-16695-1-git-send-email-virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>

On Wed, 2010-12-01 at 03:39 +0200, Alexander Shishkin wrote:
> To use this notification functionality, user has to call timerfd_settime()
> with TFD_NOTIFY_CLOCK_SET flag. After this CLOCK_REALTIME timers will
> read as the number of times the wall clock has been set since last read
> and poll every time the wall clock is set; CLOCK_MONOTONIC timers will
> behave likewise, but in the event of the clock being updated upon resuming
> from suspend. For both CLOCK_REALTIME and CLOCK_MONOTONIC timers with
> TFD_NOTIFY_CLOCK_SET flag set, a call to timerfd_gettime() will return
> current wall clock in it_value.

The CLOCK_MONOTONIC flag on resume worries me a bit (since
CLOCK_MONOTONIC isn't adjusted on resume).

What is the use case there?

thanks
-john

WARNING: multiple messages have this Message-ID (diff)
From: john stultz <johnstul@us.ibm.com>
To: Alexander Shishkin <virtuoso@slind.org>
Cc: linux-kernel@vger.kernel.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Greg Kroah-Hartman <gregkh@suse.de>,
	Feng Tang <feng.tang@intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Michael Tokarev <mjt@tls.msk.ru>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Chris Friesen <chris.friesen@genband.com>,
	Kay Sievers <kay.sievers@vrfy.org>,
	"Kirill A. Shutemov" <kirill@shutemov.name>,
	Artem Bityutskiy <dedekind1@gmail.com>,
	Davide Libenzi <davidel@xmailserver.org>,
	Lennart Poettering <mzxreary@0pointer.de>,
	linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] timerfd: add TFD_NOTIFY_CLOCK_SET to watch for clock changes
Date: Wed, 01 Dec 2010 16:14:27 -0800	[thread overview]
Message-ID: <1291248867.2846.37.camel@work-vm> (raw)
In-Reply-To: <1291167587-16695-1-git-send-email-virtuoso@slind.org>

On Wed, 2010-12-01 at 03:39 +0200, Alexander Shishkin wrote:
> To use this notification functionality, user has to call timerfd_settime()
> with TFD_NOTIFY_CLOCK_SET flag. After this CLOCK_REALTIME timers will
> read as the number of times the wall clock has been set since last read
> and poll every time the wall clock is set; CLOCK_MONOTONIC timers will
> behave likewise, but in the event of the clock being updated upon resuming
> from suspend. For both CLOCK_REALTIME and CLOCK_MONOTONIC timers with
> TFD_NOTIFY_CLOCK_SET flag set, a call to timerfd_gettime() will return
> current wall clock in it_value.

The CLOCK_MONOTONIC flag on resume worries me a bit (since
CLOCK_MONOTONIC isn't adjusted on resume).

What is the use case there?

thanks
-john



  parent reply	other threads:[~2010-12-02  0:14 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-12-01  1:39 [PATCH] timerfd: add TFD_NOTIFY_CLOCK_SET to watch for clock changes Alexander Shishkin
     [not found] ` <1291167587-16695-1-git-send-email-virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>
2010-12-02  0:14   ` john stultz [this message]
2010-12-02  0:14     ` john stultz
  -- strict thread matches above, loose matches on Subject: below --
2011-03-09 14:30 Alexander Shishkin
2011-03-09 14:30 ` Alexander Shishkin
     [not found] ` <1299681028-9112-1-git-send-email-virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>
2011-03-09 14:31   ` Alexander Shishkin
2011-03-09 14:31     ` Alexander Shishkin

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