* Can we conditionally force threading irq with primary and thread handler?
@ 2015-12-03 19:11 Yunhong Jiang
2015-12-03 22:33 ` Thomas Gleixner
0 siblings, 1 reply; 3+ messages in thread
From: Yunhong Jiang @ 2015-12-03 19:11 UTC (permalink / raw)
To: Thomas Gleixner, okuno.kohji; +Cc: linux-kernel
Hi, Thomas
On Commit 2a1d3ab8986d1b2 ("genirq: Handle force threading of irqs
with primary and thread handler"), even if the caller of
request_threaded_irq() provides a primary handler, that primary handler will
be invoked in thread context. This may cause some latency issue for high
real time requirement.
I checked the discussion on https://lkml.org/lkml/2015/9/19/372 with
Okuno and seems we need this change only if the irq is shared, otherwise, we
can still use Okuno's mechanism, am I right? Do you think it's ok to force
the primary handler for shared IRQ, otherwise, clear the IRQF_ONESHOT?
If yes, I will cook a patch for it.
Thanks
--jyh
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Can we conditionally force threading irq with primary and thread handler?
2015-12-03 19:11 Can we conditionally force threading irq with primary and thread handler? Yunhong Jiang
@ 2015-12-03 22:33 ` Thomas Gleixner
2015-12-03 22:43 ` Yunhong Jiang
0 siblings, 1 reply; 3+ messages in thread
From: Thomas Gleixner @ 2015-12-03 22:33 UTC (permalink / raw)
To: Yunhong Jiang; +Cc: okuno.kohji, linux-kernel
Yunhong,
On Thu, 3 Dec 2015, Yunhong Jiang wrote:
> Hi, Thomas
> On Commit 2a1d3ab8986d1b2 ("genirq: Handle force threading of irqs
> with primary and thread handler"), even if the caller of
> request_threaded_irq() provides a primary handler, that primary handler will
> be invoked in thread context. This may cause some latency issue for high
> real time requirement.
>
> I checked the discussion on https://lkml.org/lkml/2015/9/19/372 with
> Okuno and seems we need this change only if the irq is shared, otherwise, we
> can still use Okuno's mechanism, am I right? Do you think it's ok to force
> the primary handler for shared IRQ, otherwise, clear the IRQF_ONESHOT?
If you want to avoid that the primary handler is force threaded, then
you can indicate that with IRQF_NO_THREAD.
Thanks,
tglx
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Can we conditionally force threading irq with primary and thread handler?
2015-12-03 22:33 ` Thomas Gleixner
@ 2015-12-03 22:43 ` Yunhong Jiang
0 siblings, 0 replies; 3+ messages in thread
From: Yunhong Jiang @ 2015-12-03 22:43 UTC (permalink / raw)
To: Thomas Gleixner; +Cc: okuno.kohji, linux-kernel
On Thu, Dec 03, 2015 at 11:33:14PM +0100, Thomas Gleixner wrote:
> Yunhong,
>
> On Thu, 3 Dec 2015, Yunhong Jiang wrote:
>
> > Hi, Thomas
> > On Commit 2a1d3ab8986d1b2 ("genirq: Handle force threading of irqs
> > with primary and thread handler"), even if the caller of
> > request_threaded_irq() provides a primary handler, that primary handler will
> > be invoked in thread context. This may cause some latency issue for high
> > real time requirement.
> >
> > I checked the discussion on https://lkml.org/lkml/2015/9/19/372 with
> > Okuno and seems we need this change only if the irq is shared, otherwise, we
> > can still use Okuno's mechanism, am I right? Do you think it's ok to force
> > the primary handler for shared IRQ, otherwise, clear the IRQF_ONESHOT?
>
> If you want to avoid that the primary handler is force threaded, then
> you can indicate that with IRQF_NO_THREAD.
Thaks for reply.
Sure, will do that way. Just feel a bit weird with a valid thread_fn and a
IRQF_NO_THREAD flags.
Thanks
--jyh
>
> Thanks,
>
> tglx
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2015-12-03 19:11 Can we conditionally force threading irq with primary and thread handler? Yunhong Jiang
2015-12-03 22:33 ` Thomas Gleixner
2015-12-03 22:43 ` Yunhong Jiang
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