On Thu, 07 Apr 2011, Benjamin Herrenschmidt wrote:
>
> > > Doesn't that mean that power_pmu_read() can only ever increase the value
> > > of
> > > the perf_event and so will essentially -stop- once the counter rolls over
> > > ?
> > >
> > > Similar comments every where you do this type of comp
> > Doesn't that mean that power_pmu_read() can only ever increase the value of
> > the perf_event and so will essentially -stop- once the counter rolls over ?
> >
> > Similar comments every where you do this type of comparison.
> >
> > Cheers,
> > Ben.
>
> Sorry for the nag, but am I missing s
On Thu, 31 Mar 2011, Benjamin Herrenschmidt wrote:
> On Wed, 2011-03-30 at 14:36 -0400, Eric B Munson wrote:
> > On Wed, 30 Mar 2011, Benjamin Herrenschmidt wrote:
> >
> > > On Tue, 2011-03-29 at 10:25 -0400, Eric B Munson wrote:
> > > > Here I made the assumption that the hardware would never re
On Thu, 31 Mar 2011, Benjamin Herrenschmidt wrote:
> On Wed, 2011-03-30 at 14:36 -0400, Eric B Munson wrote:
> > On Wed, 30 Mar 2011, Benjamin Herrenschmidt wrote:
> >
> > > On Tue, 2011-03-29 at 10:25 -0400, Eric B Munson wrote:
> > > > Here I made the assumption that the hardware would never re
On Wed, 2011-03-30 at 14:36 -0400, Eric B Munson wrote:
> On Wed, 30 Mar 2011, Benjamin Herrenschmidt wrote:
>
> > On Tue, 2011-03-29 at 10:25 -0400, Eric B Munson wrote:
> > > Here I made the assumption that the hardware would never remove more
> > > events in
> > > a speculative roll back than
On Wed, 30 Mar 2011, Benjamin Herrenschmidt wrote:
> On Tue, 2011-03-29 at 10:25 -0400, Eric B Munson wrote:
> > Here I made the assumption that the hardware would never remove more events
> > in
> > a speculative roll back than it had added. This is not a situation I
> > encoutered in my limite
On Tue, 2011-03-29 at 10:25 -0400, Eric B Munson wrote:
> Here I made the assumption that the hardware would never remove more events in
> a speculative roll back than it had added. This is not a situation I
> encoutered in my limited testing, so I didn't think underflow was possible. I
> will se
On Tue, 29 Mar 2011, Benjamin Herrenschmidt wrote:
> On Fri, 2011-03-25 at 09:28 -0400, Eric B Munson wrote:
> > It is possible on POWER7 for some perf events to have values decrease. This
> > causes a problem with the way the kernel counters are updated. Deltas are
> > computed and then stored
On Fri, 2011-03-25 at 09:28 -0400, Eric B Munson wrote:
> It is possible on POWER7 for some perf events to have values decrease. This
> causes a problem with the way the kernel counters are updated. Deltas are
> computed and then stored in a 64 bit value while the registers are 32 bits
> wide so
It is possible on POWER7 for some perf events to have values decrease. This
causes a problem with the way the kernel counters are updated. Deltas are
computed and then stored in a 64 bit value while the registers are 32 bits
wide so if new value is smaller than previous value, the delta is a very
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