process wait channel (WCHAN) and alarm?

Where can I find the meaning of the different channels a process can be
waiting in? And what do the alarm values represent?
(Rightmost colums in 'ps -eo pid,user,cmd,alarm,wchan')

Hert

--
Herta Van den Eynde -=- Toledo system management
K.U. Leuven - Ludit -=- phone: +32 (0)16 322 166

"For something fulfilled this hour, loved or endured."
(W.H. Auden)


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Re: process wait channel (WCHAN) and alarm?

Herta Van den Eynde wrote:

> Where can I find the meaning of the different channels a process can be
> waiting in?

The WCHAN value is the name of the kernel function in which the
process is currently blocked.

> And what do the alarm values represent?

The delay (in seconds) of an outstanding timer, as set by alarm() or
setitimer().

--
Glynn Clements
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Re: process wait channel (WCHAN) and alarm?

Fine. I can see how alarm works.

Can you give me more details on how to find out what kernel functions
such as rt_sigsuspend, pause, ... imply?

Herta

Glynn Clements wrote:

>Herta Van den Eynde wrote:
>
>
>
>>Where can I find the meaning of the different channels a process can be
>>waiting in?
>>
>>
>
>The WCHAN value is the name of the kernel function in which the
>process is currently blocked.
>
>
>
>>And what do the alarm values represent?
>>
>>
>
>The delay (in seconds) of an outstanding timer, as set by alarm() or
>setitimer().
>
>
>

--
Herta Van den Eynde -=- Toledo system management
K.U. Leuven - Ludit -=- phone: +32 (0)16 322 166

"For something fulfilled this hour, loved or endured."
(W.H. Auden)



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Re: process wait channel (WCHAN) and alarm?

Herta Van den Eynde wrote:

> Fine. I can see how alarm works.
>
> Can you give me more details on how to find out what kernel functions
> such as rt_sigsuspend, pause, ... imply?

In many cases, the name is related to a system call, which will have a
manual page (in section 2). E.g. rt_sigsuspend suggests the
sigsuspend() system call; "man 2 sigsuspend" says (amongst other
things):

int sigsuspend(const sigset_t *mask);

...

The sigsuspend call temporarily replaces the signal mask
for the process with that given by mask and then suspends
the process until a signal is received.

Similarly, do_select() is related to select() etc.

In other cases, you might have to refer to the kernel's source code to
determine the nature of a function.

--
Glynn Clements
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