On Thu, Sep 4, 2014 at 2:36 PM, Paul Turner wrote:
> On Thu, Sep 4, 2014 at 2:30 PM, John Stultz wrote:
>> This seems to be a quite old bug.. Do you think this is needed for -stable?
>
> Seems reasonable to me.
>
I have no opinion: backport or don't at your preference.
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On Thu, Sep 4, 2014 at 2:30 PM, John Stultz wrote:
> On Thu, Sep 4, 2014 at 2:17 PM, Andrew Hunter wrote:
>> On Wed, Sep 3, 2014 at 5:06 PM, John Stultz wrote:
>>> Maybe with the next version of the patch, before you get into the
>>> unwinding the math, you might practically describe what is
On Thu, Sep 4, 2014 at 2:17 PM, Andrew Hunter wrote:
> On Wed, Sep 3, 2014 at 5:06 PM, John Stultz wrote:
>> Maybe with the next version of the patch, before you get into the
>> unwinding the math, you might practically describe what is broken,
>> then explain how its broken.
>>
>> My quick read
timeval_to_jiffies tried to round a timeval up to an integral number
of jiffies, but the logic for doing so was incorrect: intervals
corresponding to exactly N jiffies would become N+1. This manifested
itself particularly repeatedly stopping/starting an itimer:
setitimer(ITIMER_PROF, , NULL);
On Wed, Sep 3, 2014 at 5:06 PM, John Stultz wrote:
> Maybe with the next version of the patch, before you get into the
> unwinding the math, you might practically describe what is broken,
> then explain how its broken.
>
Done.
> My quick read here is that we're converting a timespec -> jiffies,
On Wed, Sep 3, 2014 at 5:06 PM, John Stultz john.stu...@linaro.org wrote:
Maybe with the next version of the patch, before you get into the
unwinding the math, you might practically describe what is broken,
then explain how its broken.
Done.
My quick read here is that we're converting a
timeval_to_jiffies tried to round a timeval up to an integral number
of jiffies, but the logic for doing so was incorrect: intervals
corresponding to exactly N jiffies would become N+1. This manifested
itself particularly repeatedly stopping/starting an itimer:
setitimer(ITIMER_PROF, val, NULL);
On Thu, Sep 4, 2014 at 2:17 PM, Andrew Hunter a...@google.com wrote:
On Wed, Sep 3, 2014 at 5:06 PM, John Stultz john.stu...@linaro.org wrote:
Maybe with the next version of the patch, before you get into the
unwinding the math, you might practically describe what is broken,
then explain how
On Thu, Sep 4, 2014 at 2:30 PM, John Stultz john.stu...@linaro.org wrote:
On Thu, Sep 4, 2014 at 2:17 PM, Andrew Hunter a...@google.com wrote:
On Wed, Sep 3, 2014 at 5:06 PM, John Stultz john.stu...@linaro.org wrote:
Maybe with the next version of the patch, before you get into the
unwinding
On Thu, Sep 4, 2014 at 2:36 PM, Paul Turner p...@google.com wrote:
On Thu, Sep 4, 2014 at 2:30 PM, John Stultz john.stu...@linaro.org wrote:
This seems to be a quite old bug.. Do you think this is needed for -stable?
Seems reasonable to me.
I have no opinion: backport or don't at your
On Thu, Aug 7, 2014 at 5:09 PM, Andrew Hunter wrote:
> timeval_to_jiffies rounding was broken. It essentially computed
> (eliding seconds)
>
> jiffies = usec * (NSEC_PER_USEC/TICK_NSEC)
>
> by using scaling arithmetic, which took the best approximation of
> NSEC_PER_USEC/TICK_NSEC with
John -- Any chance to take a look at this? (The dilation is pretty
unfortunate when profiling reprograms a timer with it.)
On Thu, Aug 7, 2014 at 5:09 PM, Andrew Hunter wrote:
> timeval_to_jiffies rounding was broken. It essentially computed
> (eliding seconds)
>
> jiffies = usec *
John -- Any chance to take a look at this? (The dilation is pretty
unfortunate when profiling reprograms a timer with it.)
On Thu, Aug 7, 2014 at 5:09 PM, Andrew Hunter a...@google.com wrote:
timeval_to_jiffies rounding was broken. It essentially computed
(eliding seconds)
jiffies = usec *
On Thu, Aug 7, 2014 at 5:09 PM, Andrew Hunter a...@google.com wrote:
timeval_to_jiffies rounding was broken. It essentially computed
(eliding seconds)
jiffies = usec * (NSEC_PER_USEC/TICK_NSEC)
by using scaling arithmetic, which took the best approximation of
NSEC_PER_USEC/TICK_NSEC with
timeval_to_jiffies rounding was broken. It essentially computed
(eliding seconds)
jiffies = usec * (NSEC_PER_USEC/TICK_NSEC)
by using scaling arithmetic, which took the best approximation of
NSEC_PER_USEC/TICK_NSEC with denominator of 2^USEC_JIFFIE_SC =
x/(2^USEC_JIFFIE_SC), and computed:
timeval_to_jiffies rounding was broken. It essentially computed
(eliding seconds)
jiffies = usec * (NSEC_PER_USEC/TICK_NSEC)
by using scaling arithmetic, which took the best approximation of
NSEC_PER_USEC/TICK_NSEC with denominator of 2^USEC_JIFFIE_SC =
x/(2^USEC_JIFFIE_SC), and computed:
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