Re: [boost] [Chrono] Proposed library now feature complete

Subject: Re: [boost] [Chrono] Proposed library now feature complete
From: vicente.botet (vicente.botet_at_[hidden])
Date: 2008-11-18 18:05:22

----- Original Message ----- 
From: "Beman Dawes" <bdawes_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Tuesday, November 18, 2008 11:03 PM
Subject: Re: [boost] [Chrono] Proposed library now feature complete

> 
> On Tue, Nov 18, 2008 at 1:40 PM, vicente.botet <vicente.botet_at_[hidden]> wrote:
> 
>> As you have started to add other features in addition to the ratio+chrono libraries, I was wondering if in addition to procees CPU usage you can add thread CPU usage. What about  CPU% for process and a threads?
> 
> The need that comes up over and over is for wall-clock time, and per
> process cpu user and system time. And that's what POSIX times() and
> equivalent Win32 functions have provided for many years.
> 
> On some operating systems there are lots of other times available, but
> I have no idea if these other times have portable equivalents. Did you
> have something specific in mind, or was it a theoretical question?

In Linux each thread is seen as a process, so it is posible to obtain the CPU usage of a thread.
In fault taulerant systems, a thread that loops (BUG) would take a high CPU%. This can be used to detect this kind of situation and abort the process.

>> Are these in the scope of your library?
>>
>> process_timer gives real, user and system times. What about iowait?
> 
> It would be useful if generally available. Ideas for how to measure on
> Windows and POSIX would be appreciated.

I don't know Windows at all. In unix like systems you find these informations on the /proc/'pid'/stat.

Regards,
Vicente