From: Rik van Riel <riel@redhat.com>
To: linux@horizon.com
Cc: learninglinux4@gmail.com, linux-kernel@vger.kernel.org,
linux-newbie@vger.kernel.org
Subject: Re: Why can't we sleep in an ISR?
Date: Mon, 14 May 2007 11:55:10 -0400 [thread overview]
Message-ID: <4648865E.5030706@redhat.com> (raw)
In-Reply-To: <20070514152218.19773.qmail@science.horizon.com>
linux@horizon.com wrote:
> Sleeping in an ISR is not fundamentally impossible - I could design
> a multitasker that permitted it - but has significant problems, and
> most multitaskers, including Linux, forbid it.
You could design a system in which most ISRs can sleep,
but even then you'll probably need to make exceptions.
For example, the timer interrupt tends to drive the
scheduler. This means the timer interrupt cannot go
to sleep and expect the scheduler to wake it up at
some point in the future - since there will be no new
timer interrupts to drive the scheduler.
This precludes the timer interrupt from taking certain
sleeping locks, even on a system where interrupts can
sleep (not Linux).
Interrupts will always have some limitations, under
any OS design.
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next prev parent reply other threads:[~2007-05-14 15:55 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-14 15:22 Why can't we sleep in an ISR? linux
2007-05-14 15:55 ` Rik van Riel [this message]
-- strict thread matches above, loose matches on Subject: below --
2007-05-15 9:34 rohit hooda
2007-05-15 9:46 ` pradeep singh
2007-05-14 6:37 Learning Linux
2007-05-14 7:10 ` pradeep singh
2007-05-14 7:16 ` Learning Linux
2007-05-14 15:24 ` Bahadir Balban
2007-05-14 15:56 ` Dong Feng
2007-05-15 5:17 ` pradeep singh
2007-05-15 6:45 ` Dong Feng
2007-05-15 7:10 ` pradeep singh
2007-05-15 7:28 ` Dong Feng
2007-05-15 8:12 ` pradeep singh
2007-05-15 8:40 ` Learning Linux
2007-05-15 8:58 ` Dong Feng
2007-05-15 16:57 ` Phillip Susi
2007-05-15 22:49 ` Dong Feng
2007-05-16 15:20 ` Phillip Susi
2007-05-16 23:17 ` Dong Feng
2007-05-17 16:07 ` Phillip Susi
2007-05-17 23:50 ` Dong Feng
2007-05-14 12:25 ` Helge Hafting
2007-05-14 12:52 ` pradeep singh
2007-05-14 13:36 ` Dong Feng
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