linux-kernel - Re: preempt_disable and sleep()

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Message-ID: <AANLkTilMrwdaLrTAUVETYZLYSpoqVFVXfKZ2lZit6uG3@mail.gmail.com>
Date:	Fri, 14 May 2010 08:16:07 +0530
From:	ratheesh k <ratheesh.ksz@...il.com>
To:	Sven-Thorsten Dietrich <thebigcorporation@...il.com>
Cc:	linux-kernel@...r.kernel.org, linux-rt-users@...r.kernel.org
Subject: Re: preempt_disable and sleep()

On Fri, May 14, 2010 at 12:13 AM, Sven-Thorsten Dietrich
<thebigcorporation@...il.com> wrote:

> Why would you do this?
I was reading some linux kernel journel about preempt_disable() . This
a doubt came to me .


> If you had tried this code, you would have seen the corresponding stack
> dump on the console.


Why it so .? could you explain a little more ? .sleep() will schedule
() , which inturn give back control to kernel .

Thank,
Ratheesh

On Fri, May 14, 2010 at 12:13 AM, Sven-Thorsten Dietrich
<thebigcorporation@...il.com> wrote:
> On Fri, 2010-05-14 at 00:02 +0530, ratheesh k wrote:
>> I am running RT linux .
>>
>> /* code snippet */
>>
>> preempt_disable()
>> ...........
>> sleep(10);
>> '............
>> preempt_enable()
>>
>>
>> will this sleep() will cause reschedule ?.
>>
>
> Why would you do this?
>
> If you had tried this code, you would have seen the corresponding stack
> dump on the console.
>
>> if an interrupt comes  while premption is disabled , how it is handled ?.
>>
>
> Depends on the number of (idle) cores, the setting of CONFIG_PREEMPT_[]
> and the type of interrupt.
>
> RT threaded IRQs would not run until preemption is enabled on a single
> core system.
>
>
>
>> Thanks,
>> Ratheesh
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>
>
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