Messages in this thread | | | Date | Mon, 9 Feb 2009 10:00:58 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [RFC git tree] Userspace RCU (urcu) for Linux (repost) |
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On Mon, Feb 09, 2009 at 12:42:02PM -0500, Mathieu Desnoyers wrote: > * 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/$pid/tasks/*`? Or is this not > > > >> atomic enough? > > > > > > > > Won't that give me all the threads rather than only the ones currently > > > > running? > > > > > > What do you mean by 'running'? > > > > Sitting on a CPU and executing, as opposed to blocked or preempted. > > > > It is pretty easy to scan the running tasks within the kernel, but I > > don't know of an efficient way to do it from user mode. The only way > > I know of would be to cat out the /proc/$pid/tasks/*/status (IIRC) > > and look for the task state. > > The thing I dislike about this approach is the non-portability. Ideally, > if we want to integrate urcu to pthreads, we should also aim at > BSD-based OSes.
But it could be portable. If the /proc file in question could not be opened (as would be the case on BSDs), you just send the signal to all the tasks.
Thanx, Paul
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