All of lore.kernel.org
 help / color / mirror / Atom feed
From: David Engraf <david.engraf@sysgo.com>
To: John Stultz <johnstul@us.ibm.com>, Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Subject: timekeeping_adjust may set mult to 0
Date: Mon, 11 Feb 2013 16:48:11 +0100	[thread overview]
Message-ID: <511912BB.2060602@sysgo.com> (raw)

Hi,

I have encountered a problem when a linux system uses a clocksource with 
mult = 1 and shift = 0 (clocksource cycle = nanoseconds). It may happen 
that the function timekeeping_adjust reduces the value of mult to 0 when 
error is lower than the interval [1].
As soon as timekeeper.mult is 0, ktime_get will no longer work because 
it uses timekeeping_get_ns which converts the cycle to nanoseconds with 
mult as 0 and the system clocksource returns always 0.

Best regards
David Engraf


[1] http://lxr.linux.no/linux+v3.0.62/kernel/time/timekeeping.c#L821

             reply	other threads:[~2013-02-11 15:57 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-02-11 15:48 David Engraf [this message]
2013-02-15 22:34 ` timekeeping_adjust may set mult to 0 John Stultz
2013-02-26 13:05   ` David Engraf

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=511912BB.2060602@sysgo.com \
    --to=david.engraf@sysgo.com \
    --cc=johnstul@us.ibm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=tglx@linutronix.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.