From: george anzinger <george@mvista.com>
To: Robert Love <rml@tech9.net>
Cc: root@chaos.analogic.com, sanket rathi <sanket@linuxmail.org>,
linux-kernel@vger.kernel.org
Subject: Re: interrupt handler
Date: Fri, 23 Aug 2002 13:45:05 -0700 [thread overview]
Message-ID: <3D669ED1.402D1432@mvista.com> (raw)
In-Reply-To: 1030121541.1935.3684.camel@phantasy
Robert Love wrote:
>
> On Fri, 2002-08-23 at 12:45, Richard B. Johnson wrote:
>
> > On 23 Aug 2002, Robert Love wrote:
> > > Only the current interrupt handler is disabled... interrupts are
> > > normally ON.
> >
> > No. Check out irq.c, line 446. The interrupts are turned back on
> > only if the flag did not have SA_INTERRUPT set. Certainly most
> > requests for interrupt services within drivers have SA_INTERRUPT
> > set.
>
> Sigh... SA_INTERRUPT is used only for fast interrupts. Certainly most
> drivers do not have it (and most that do are probably from the way old
> days when we went through great pains to distinguish between fast and
> slow interrupt handlers).
>
> Today, very few things should run with all interrupts disabled. That is
> just dumb. In fact, on this system, it seems only the timer interrupt
> sets SA_INTERRUPT...
>
And THAT makes sense as most of the timer interrupt is
processed holding the write_lock() on xtime which would need
to be an irq lock otherwise. If they were turned on the
system would have an additional interrupts on/off overhead.
> Robert Love
>
> -
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> Please read the FAQ at http://www.tux.org/lkml/
--
George Anzinger george@mvista.com
High-res-timers:
http://sourceforge.net/projects/high-res-timers/
Preemption patch:
http://www.kernel.org/pub/linux/kernel/people/rml
next prev parent reply other threads:[~2002-08-23 20:41 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-08-23 11:58 interrupt handler sanket rathi
2002-08-23 12:17 ` Richard B. Johnson
2002-08-23 16:17 ` Robert Love
2002-08-23 16:45 ` Richard B. Johnson
2002-08-23 16:52 ` Robert Love
2002-08-23 20:45 ` george anzinger [this message]
-- strict thread matches above, loose matches on Subject: below --
2004-04-15 10:02 Interrupt handler MNH
2004-04-17 18:57 ` Karim Yaghmour
2002-08-23 6:22 interrupt handler Kerenyi Gabor
2002-08-23 5:45 Kerenyi Gabor
2002-08-23 13:07 ` Richard B. Johnson
2002-08-23 4:58 Kerenyi Gabor
2002-08-21 14:25 Interrupt Handler sanket rathi
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