On Thu, 21 Apr 2005, Chris Friesen wrote:
>
> Does mainline have a high precision monotonic wallclock that is not
> affected by time-of-day changes? Something like "nano/mico seconds
> since boot"?
On newer kernels with the posix timers (I think 2.6 - not sure though)
there's clock_gettime(CLOC
On Thu, 21 Apr 2005, Chris Friesen wrote:
>
> Does mainline have a high precision monotonic wallclock that is not
> affected by time-of-day changes? Something like "nano/mico seconds
> since boot"?
High precision? No. We do have "jiffies since boot". We don't actually
expose it anywhere, alt
Linus Torvalds wrote:
If you calculate the expected timeout from the time-of-day in the caller,
your drift not only goes away, but you'll actually be able to handle
things like "oops, the machine is under load so I missed an event".
Does mainline have a high precision monotonic wallclock that is n
On Thu, 2005-04-21 at 07:58 -0700, Linus Torvalds wrote:
>
> On Thu, 21 Apr 2005, Steven Rostedt wrote:
> >
> > Thanks, I forgot about the guarantee of "at least" the time requested.
> > I took this on because I noticed this in a driver I wrote. With the user
> > passing in a timeval for a period
On Thu, 21 Apr 2005, Steven Rostedt wrote:
>
> Thanks, I forgot about the guarantee of "at least" the time requested.
> I took this on because I noticed this in a driver I wrote. With the user
> passing in a timeval for a periodic condition. I noticed that this would
> drift quite a bit.
Your u
On Thu, 2005-04-21 at 09:51 +0100, Russell King wrote:
[...]
> The problem is that when you add a timer, you don't have any idea
> which point you're going to be starting your timer at.
>
> This is why we always round up to the next jiffy when we convert
> times to jiffies - this ensures that you
On Wed, Apr 20, 2005 at 11:40:16PM -0400, Steven Rostedt wrote:
> Is 11 jiffies correct for 10ms?
Consider the 1 jiffy case. How long does waiting one jiffy actually wait?
j=01 2
+--+--+--> t
A B C D
If you start timing one jiffy from A
On Wed, 2005-04-20 at 22:58 -0400, Steven Rostedt wrote:
> I looked into the problem that jdavis had and found that the conversion
> of the timeval_to_jiffies was off by one.
>
> To convert tv.tv_sec = 0, tv.tv_usec = 1 to jiffies, you come up
> with an answer of 11 (assuming 1000 HZ).
>
I looked into the problem that jdavis had and found that the conversion
of the timeval_to_jiffies was off by one.
To convert tv.tv_sec = 0, tv.tv_usec = 1 to jiffies, you come up
with an answer of 11 (assuming 1000 HZ).
Here's the patch:
--- ./include/linux/jiffies.h.orig 2005-04-20
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