Re: Blocking syscalls in Tasks

["Hibou57 (Yannick Duchêne)" <yannick_duchene@yahoo.fr>]

On 27 sep, 19:26, schwer...@gmail.com wrote:
> Hi there,
>
> I'm wondering whether a blocking system call like read() called via C
> interfacing in a task would block only the task or the complete
> process.
>
> Are tasks commonly implemented using threads and does the language
> specification request tasks to be in the user- or kernelspace? Or is
> there a real difference between tasks and threads?
>
> Greetings and thanks in advance
>
> Chris

Hello Chris,

I've tryed to check for a reliable references, and found something
which may help you to make some assertion. It seems that it is thread/
task blocking rather than process blocking. This is based on mail
exchanged by developpers of the Linux kernel. It is dated Sun, 12 Aug
2007, so do not make assertion using this about too much old kernels
(you did not say what kernel version you use, neither if it is a
vanilla one or not)

Here is the link to the mail at the LKML mail archives :
http://lkml.org/lkml/2007/8/12/102

It explains how with older kernel version, two thread may be
simultaneously blocked in some way, and talk about a patch to help
threads to not indefinitely bock on some IO events.

This talks about thread (or task) blocking, not process. And further
more, it explicitely talk about two thread in a process which do
theire own work simultaneously whithout them to be required to be both
block by an IO operation of one alone.

Do you think this is relevant and/or of interest for your stuff ?