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Date: Mon, 9 Feb 2009 18:45:05 +0100
Message-ID: <36ca99e90902090945t8ae9792j84ca940f62414a48@mail.gmail.com>
Subject: Re: [RFC git tree] Userspace RCU (urcu) for Linux (repost)
From: Bert Wesarg <bert.wesarg@googlemail.com>
To: paulmck@linux.vnet.ibm.com
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>,
       ltt-dev@lists.casi.polymtl.ca, linux-kernel@vger.kernel.org,
       Robert Wisniewski <bob@watson.ibm.com>
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On Mon, Feb 9, 2009 at 18:40, Paul E. McKenney
<paulmck@linux.vnet.ibm.com> wrote:
> On Mon, Feb 09, 2009 at 06:35:38PM +0100, Bert Wesarg wrote:
>> On Mon, Feb 9, 2009 at 18:34, Paul E. McKenney
>> <paulmck@linux.vnet.ibm.com> wrote:
>> > On Mon, Feb 09, 2009 at 06:19:45PM +0100, Bert Wesarg wrote:
>> >> On Mon, Feb 9, 2009 at 14:16, Paul E. McKenney
>> >> <paulmck@linux.vnet.ibm.com> wrote:
>> >> > On Sun, Feb 08, 2009 at 11:53:52PM -0500, Mathieu Desnoyers wrote:
>> >> >> Yes, I guess the signal is not so bad.
>> >> >
>> >> > Now if there were a /proc entry that listed out the tids of the
>> >> > currently running threads, then it might be possible to do something,
>> >> > especially for applications with many more threads than CPUs.
>> >>
>> >> Do you mean something like: `ls /proc/$pid/tasks/*`? Or is this not
>> >> atomic enough?
>> >
>> > Won't that give me all the threads rather than only the ones currently
>> > running?
>>
>> What do you mean by 'running'?
>
> Sitting on a CPU and executing, as opposed to blocked or preempted.
Ok, me too.

>
> It is pretty easy to scan the running tasks within the kernel, but I
> don't know of an efficient way to do it from user mode.  The only way
> I know of would be to cat out the /proc/$pid/tasks/*/status (IIRC)
> and look for the task state.
Yes, me too.

Bert
>
>                                                        Thanx, Paul
>