From mboxrd@z Thu Jan  1 00:00:00 1970
From: compudj@krystal.dyndns.org (Mathieu Desnoyers)
Date: Fri, 17 Oct 2008 12:28:49 -0400
Subject: [ltt-dev] sys time
In-Reply-To: <48F8AEBD.2030303@polymtl.ca>
References: <8d94e9280810170558j5b9ed8d1q7da37da677c7bf7d@mail.gmail.com>
	<8d94e9280810170606o729767f3p839c1c3a59c9565d@mail.gmail.com>
	<48F8AEBD.2030303@polymtl.ca>
Message-ID: <20081017162849.GD5696@Krystal>

* Pierre-Marc Fournier (pierre-marc.fournier at polymtl.ca) wrote:
> Gian Lorenzo Meocci wrote:
> 
> > I want to know if it is possible to obtain this results using lttng trace.
> 
> It is definitely possible.
> 
> > Actually I made a sum of all differences from a
> > kernel_arch_trap_entry/kernel_arch_trap_exit,
> > kernel_arch_syscall_entry/exit, kernel_softirq_entry/exit,
> > mm_handle_fault_entry/exit, kernel_irq_entry/exit.
> 
> You don't need mm_handle_fault_entry/exit because they are always
> enclosed within kernel_arch_trap_entry/exit's.
> 
> > But for now, my results isn't very good.
> 
> - You need to stop counting time when your process is being scheduled
> out. See the kernel_sched_schedule events.
> 
> - You need to filter the events based on the pid of the process you're
> investigating, but I guess you're already doing that.
> 
> - If the process is being created inside the trace, you need to start
> counting time only after it is created, of course. You could count
> syscall time starting at the kernel_process_fork that creates the
> process. Also, you need to stop counting time when it's destroyed of course.
> 
> - If the process already exists when the trace is started, only consider
> events after the list_statedump_end event. Before that, the pid of each
> event might not be reliable.
> 

All the above is good. Another thing : if an interrupt handler is
executed on top of system call code, don't count it twice. :)

Mathieu

> pmf
> 
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-- 
Mathieu Desnoyers
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