On Wed, 2016-02-24 at 22:00 -0500, Ashutosh Dixit wrote:
> On Tue, Feb 23 2016 at 06:57:28 AM, Andy Shevchenko <andriy.shevchenk
> o@xxxxxxxxxxxxxxx> wrote:
> > > +/* ASPM processing for each receive context interrupt */
> > > +static inline void aspm_ctx_disable(struct hfi1_ctxtdata *rcd)
> > > +{
> > > + bool restart_timer;
> > > + bool close_interrupts;
> > > + unsigned long flags;
> > > + ktime_t now, prev;
> > > +
> > > + /* Quickest exit for minimum impact */
> > > + if (!rcd->aspm_intr_supported)
> > > + return;
> > > +
> > > + spin_lock_irqsave(&rcd->aspm_lock, flags);
> > > + /* PSM contexts are open */
> > > + if (!rcd->aspm_intr_enable)
> > > + goto ret;
> > > +
> > > + prev = rcd->aspm_ts_last_intr;
> > > + now = ktime_get();
> > > + rcd->aspm_ts_last_intr = now;
> > > +
> > > + /* An interrupt pair close together in time */
> > > + close_interrupts = ktime_to_ns(ktime_sub(now, prev)) <
> > > ASPM_TRIGGER_NS;
> > > +
> > > + /* Don't push out our timer till this much time has
> > > elapsed
> > > */
> > > + restart_timer = ktime_to_ms(ktime_sub(now, rcd-
> > > > aspm_ts_timer_sched)) >
> > > + ASPM_RESCHED_TIMER_MS;
> >
> > > + restart_timer = restart_timer && close_interrupts;
> > > +
> > > + /* Disable ASPM and schedule timer */
> > > + if (rcd->aspm_enabled && close_interrupts) {
> > > + aspm_disable_inc(rcd->dd);
> > > + rcd->aspm_enabled = false;
> > > + restart_timer = true;
> > > + }
> > > +
> > > + if (restart_timer) {
> > > + mod_timer(&rcd->aspm_timer,
> > > + jiffies +
> > > msecs_to_jiffies(ASPM_TIMER_MS));
> > > + rcd->aspm_ts_timer_sched = now;
> > > + }
> >
> > What about the following changes (mostly about replacing divisions
> > by
> > multiplications)?
> >
> >
> > ktime_t eta, restart;
> >
> > eta = ktime_add_ns(rcd->aspm_ts_last_intr, ASPM_TRIGGER_NS);
> >
> > rcd->aspm_ts_last_intr = ktime_get();
> >
> > /* Close interrupts? */
> > if (ktime_before(now, eta)) {
> > /* Disable ASPM? */
> > if (rcd->aspm_enabled) {
> >
> > aspm_disable_inc(rcd->dd);
> > rcd->aspm_enabled = false;
> > } else {
> >
> > restart = ktime_add_ms(rcd->aspm_ts_timer_sched,
> > ASPM_RESCHED_TIMER_MS);
> > if (ktime_before(rcd->aspm_ts_last_intr,
> > restart))
> > goto exit_unlock;
> > }
> >
> > /* Restart timer */
> > mod_timer(&rcd->aspm_timer, jiffies +
> > msecs_to_jiffies(ASPM_TIMER_MS));
> > rcd->aspm_ts_timer_sched = rcd->aspm_ts_last_intr;
> > }
>
> There are no divisions in the code segment above. We discussed it
> internally and there is agreement to leave the patch as is.
Right, this is just a comment not to be missed in the future version, I
hope.
--
Andy Shevchenko <andriy.shevchenko@xxxxxxxxx>
Intel Finland Oy
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