Message-ID: <48673873.6040202@davidnewall.com>
Date: Sun, 29 Jun 2008 16:53:31 +0930
From: David Newall <davidn@davidnewall.com>
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To: Jeremy Fitzhardinge <jeremy@goop.org>
CC: =?ISO-8859-1?Q?T=F6r=F6k_Edwin?= <edwintorok@gmail.com>,
       Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: Ctrl+C doesn't interrupt process waiting for I/O
References: <48661488.10304@gmail.com> <4866F6FE.9000503@goop.org>
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Jeremy Fitzhardinge wrote:
> T?r?k Edwin wrote:
>> ...
>> - I have a (I/O bound) process running in my terminal, and I want to
>> interrupt it with Ctrl+C
>>  - I type Ctrl+C several times, and the process is not interrupted for
>> several seconds (10-30 secs)
>>  - if I type Ctrl+Z, and use kill %1 the process dies faster than
>> waiting for it to react to Ctrl+C  
>
> Yes, it's intended behaviour.  Filesystem IO syscalls are considered
> "fast" and are interruptible.  Usermode code can reasonably expect
> that file IO will never return EINTR.

This does not address the symptom that the process can be killed quicker
by sending a SIGTERM.  I've noticed the problem, too (2.6.25.)  I wonder
if it isn't some strangeness in the tty layer (hence the interrupt key
is slower than an explicitly sent signal.)
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