[ECOS] confused about Interrupt handling.

[ECOS] confused about Interrupt handling.

[Tony Ko]

hi.
compare two sentences below

"For this to work in the presence of interrupts, it is necessary for
the Interrupt Service Routines (ISR) to defer any scheduler-oriented
operations until the lock is about to go zero. We do this by splitting
the work of an ISR into two parts, with the second part, the Deferred
Service Routine ( DSR ), being queued until the scheduler decides it is
safe to run. "


" After the ISR exits, but before the kernel scheduler is invoked
again, a delayed service routine ( DSR ) will be invoked. It executes
with scheduling disabled, but with interrupts enabled, so that further
invocations of the same DSR can be queued."

these two sentences are from ecos-ref.4.

I'm confused  about " actually when DSR process".
After scheduling invoked again  or  Before scheduling invoked again?

I think DSR is a kind of scheduler-oriented operation, right?

thanks in advance.

Tony.

Re: [ECOS] confused about Interrupt handling.

[Jonathan Larmour]

Tony Ko wrote:
> 
> hi.
> compare two sentences below
> 
> "For this to work in the presence of interrupts, it is necessary for
> the Interrupt Service Routines (ISR) to defer any scheduler-oriented
> operations until the lock is about to go zero. We do this by splitting
> the work of an ISR into two parts, with the second part, the Deferred
> Service Routine ( DSR ), being queued until the scheduler decides it is
> safe to run. "
> 
> " After the ISR exits, but before the kernel scheduler is invoked
> again, a delayed service routine ( DSR ) will be invoked. It executes
> with scheduling disabled, but with interrupts enabled, so that further
> invocations of the same DSR can be queued."
> 
> these two sentences are from ecos-ref.4.
> 
> I'm confused  about " actually when DSR process".
> After scheduling invoked again  or  Before scheduling invoked again?

The scheduler must call a DSR straight away if it is safe to so (dependent
on the scheduler lock) before it can do any scheduling.
 
> I think DSR is a kind of scheduler-oriented operation, right?

I'm not sure it can be described in those terms. It's a routine that runs
while scheduling does not happen.

Jifl
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