irq: implement IRQ expecting
in [Kernel]
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From: Jiri Slaby on 14 Jun 2010 05:30 On 06/13/2010 05:31 PM, Tejun Heo wrote: > --- a/kernel/irq/spurious.c > +++ b/kernel/irq/spurious.c .... > @@ -25,9 +26,43 @@ enum { > /* IRQ polling common parameters */ > IRQ_POLL_SLOW_INTV = 3 * HZ, /* not too slow for ppl, slow enough for machine */ > IRQ_POLL_INTV = HZ / 100, /* from the good ol' 100HZ tick */ > + IRQ_POLL_QUICK_INTV = HZ / 1000, /* pretty quick but not too taxing */ > > IRQ_POLL_SLOW_SLACK = HZ, > IRQ_POLL_SLACK = HZ / 1000, /* 10% slack */ > + IRQ_POLL_QUICK_SLACK = HZ / 10000, /* 10% slack */ Hi. These are zeros on most systems (assuming distros set HZ=100 and 250), what is their purpose then? regards, -- js -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Tejun Heo on 14 Jun 2010 05:50 On 06/14/2010 11:43 AM, Tejun Heo wrote: > Hello, > > On 06/14/2010 11:21 AM, Jiri Slaby wrote: >> On 06/13/2010 05:31 PM, Tejun Heo wrote: >>> --- a/kernel/irq/spurious.c >>> +++ b/kernel/irq/spurious.c >> ... >> >>> @@ -25,9 +26,43 @@ enum { >>> /* IRQ polling common parameters */ >>> IRQ_POLL_SLOW_INTV = 3 * HZ, /* not too slow for ppl, slow enough for machine */ >>> IRQ_POLL_INTV = HZ / 100, /* from the good ol' 100HZ tick */ >>> + IRQ_POLL_QUICK_INTV = HZ / 1000, /* pretty quick but not too taxing */ >>> >>> IRQ_POLL_SLOW_SLACK = HZ, >>> IRQ_POLL_SLACK = HZ / 1000, /* 10% slack */ >>> + IRQ_POLL_QUICK_SLACK = HZ / 10000, /* 10% slack */ >> >> Hi. These are zeros on most systems (assuming distros set HZ=100 and >> 250), what is their purpose then? > > On every tick and no slack. :-) Hmmm... but yeah, it would be better to make IRQ_POLL_SLACK HZ / 250 so that we at least have one tick slack on 250HZ configs which are pretty common these days. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Arjan van de Ven on 17 Jun 2010 00:00 On Sun, 13 Jun 2010 17:31:35 +0200 Tejun Heo <tj(a)kernel.org> wrote: > + */ > +void expect_irq(struct irq_expect *exp) I would like to suggest an (optional) argument to this with a duration within which to expect an interrupt.... that way in the backend we can plumb this also into the idle handler for C state selection... -- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Tejun Heo on 17 Jun 2010 04:30 Hello, Arjan. On 06/17/2010 05:48 AM, Arjan van de Ven wrote: > On Sun, 13 Jun 2010 17:31:35 +0200 > Tejun Heo <tj(a)kernel.org> wrote: >> + */ >> +void expect_irq(struct irq_expect *exp) > > I would like to suggest an (optional) argument to this with a duration > within which to expect an interrupt.... > > that way in the backend we can plumb this also into the idle handler > for C state selection... Hmmm.... oh, I see. Wouldn't it be much better to use moving avg of IRQ durations instead of letting the driver specify it? Drivers are most likely to just hard code it and It's never gonna be accurate. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Thomas Gleixner on 17 Jun 2010 07:20
On Thu, 17 Jun 2010, Tejun Heo wrote: > Hello, Arjan. > > On 06/17/2010 05:48 AM, Arjan van de Ven wrote: > > On Sun, 13 Jun 2010 17:31:35 +0200 > > Tejun Heo <tj(a)kernel.org> wrote: > >> + */ > >> +void expect_irq(struct irq_expect *exp) > > > > I would like to suggest an (optional) argument to this with a duration > > within which to expect an interrupt.... > > > > that way in the backend we can plumb this also into the idle handler > > for C state selection... > > Hmmm.... oh, I see. Wouldn't it be much better to use moving avg of > IRQ durations instead of letting the driver specify it? Drivers are > most likely to just hard code it and It's never gonna be accurate. Right, but that's probably more accurate than the core code heuristics ever will be. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |