Messages in this thread | | | Subject | Re: [Patch 4/7] Add sysctl for delay accounting | From | Arjan van de Ven <> | Date | Mon, 27 Feb 2006 10:13:14 +0100 |
| |
On Mon, 2006-02-27 at 14:34 +0530, Dipankar Sarma wrote: > On Mon, Feb 27, 2006 at 09:42:23AM +0100, Arjan van de Ven wrote: > > On Mon, 2006-02-27 at 03:38 -0500, Shailabh Nagar wrote: > > > Arjan van de Ven wrote: > > > > > > The function needs to allocate task_delay_info structs for all tasks > > > that might > > > have been forked since the last time delay accounting was turned off. > > > Either we have to count how many such tasks there are, or preallocate > > > nr_tasks (as an upper bound) and then use as many as needed. > > > > it generally feels really fragile, especially with the task enumeration > > going to RCU soon. (eg you'd lose the ability to lock out new task > > creation) > > I haven't yet seen any RCU-based code that does this. Can you point out > what patches you are talking about ? As of 2.6.16-rc4 and -rt15, > AFAICS, you can count tasks by holding the read side of tasklist_lock. > Granted it is a bit ugly to repeat this in order to overcome > the race on dropping tasklist_lock for allocation.
there are several people (Christoph for one) who are working on making the tasklist_lock go away entirely in favor of RCU-like locking...
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |