On Fri, Apr 27, 2007 at 11:52:47AM +0400, Oleg Nesterov wrote: > On 04/27, Jarek Poplawski wrote: ... > > > Sorry, can't understand. done == 0 means that the queueing in progress, > > > this work should be placed on cwq->worklist very soon, most probably > > > right after we drop cwq->lock. > > > > I think, theoretically, probably, maybe, there is possible some strange > > case, this function gets spin_lock only when: list_empty(&work->entry) == 1 > > && _PENDING == 1 && del_timer(&dwork->timer) == 0. > > Yes, but this is not so strange, this means the queueing in progress. Most > probably the "owner" of WORK_STRUCT_PENDING bit spins waiting for cwq->lock. > We will retry in this case. Of course, if we have a workqueue with the single > work which just re-arms itself via queue_work() (without delay) and does > nothing > more, we may need a lot of looping.
I've forgot most of the math already, but there is (probably) some Parkinson's Law about it. So, by this strange case I mean really lot of looping (something around infinity - quite precisely). > > > PS: probably unusable, but for my own satisfaction: > > > > Acked-by: Jarek Poplawski <[EMAIL PROTECTED]> > > It is useable, at least for me. I hope you will re-ack when I actually send This is even more strange... BTW, I take a week of vacation (people here deserve to rest from me), so let's say it's both acked and re-acked by me. > the patch. Note that the "else" branch above doesn't need cwq->lock, and we > should start with del_timer(), because the pending timer is the most common > case. I see, you've thought about it probably more than you said so, I trust you 100% here (but will check later, anyway...). Cheers, Jarek P. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
