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Re: what's a good thing for using DSR when interrupt happen ???
- To: Tony Ko <nhko at gctsemi dot com>
- Subject: Re: [ECOS] what's a good thing for using DSR when interrupt happen ???
- From: Jonathan Larmour <jlarmour at redhat dot com>
- Date: Thu, 06 Sep 2001 21:49:33 +0100
- Cc: ecos-discuss at sources dot redhat dot com
- Organization: Red Hat UK Ltd.
- References: <9860C773D04D834D83FD6FAD00A61E9311B71D@gctsemi.gctsemi.com>
Tony Ko wrote:
>
> hi.
> I understand DSR is used for scheduling-based-process for interrupt
> hadling.
> and I know DSR is used to avoid frequent ISR.
>
> but what about this case, serial port interrupt ?
> when interrupt occur, ISR is called and the ISR makes DSR called later.
> and then, when finishing ISR, Kernel schedules again, then DSR is
> called first than other ready-state -thread.
> in this case, DSR is called right after ISR.
> then, what's good thing for using DSR?
Another interrupt can interrupt the DSR. But not an ISR. This won't be much
of an issue if you only really get one interrupt as (in general) you will
mask the interrupt in the ISR and unmask it in the DSR. But in the general
case, it is an issue, hence the split.
Jifl
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