On Tue, Sep 05, 2017 at 09:38:45AM +0900, Byungchul Park wrote: > On Mon, Sep 04, 2017 at 01:42:48PM +0200, Peter Zijlstra wrote: > > On Mon, Sep 04, 2017 at 10:30:32AM +0900, Byungchul Park wrote: > > > On Fri, Sep 01, 2017 at 06:38:52PM +0200, Peter Zijlstra wrote: > > > > And get tangled up with the workqueue annotation again, no thanks. > > > > Having the first few works see the thread setup isn't worth it. > > > > > > > > And your work_id annotation had the same problem. > > > > > > I keep asking you for an example because I really understand you. > > > > > > Fix my problematic example with your patches, > > > > > > or, > > > > > > Show me a problematic scenario with my original code, you expect. > > > > > > Whatever, it would be helpful to understand you. > > > > I _really_ don't understand what you're worried about. Is it the kthread > > create and workqueue init or the pool->lock that is released/acquired in > > process_one_work()? > > s/in process_one_work()/in all worker code including setup code/ > > Original code was already designed to handle real dependencies well. But > you invalidated it _w/o_ any reason, that's why I don't agree with your > patches.
The reasons: - it avoids the interaction with the workqueue annotation - it makes each work consistent - its not different from what you did with work_id: https://lkml.kernel.org/r/1489479542-27030-6-git-send-email-byungchul.p...@lge.com crossrelease_work_start() vs same_context_xhlock() { if (xhlock->work_id == curr->workid) ... } > Your patches only do avoiding the wq issue now we focus on. > > Look at: > > worker thread another context > ------------- --------------- > wait_for_completion() > | > | (1) > v > +---------+ > | Work A | (2) > +---------+ > | > | (3) > v > +---------+ > | Work B | (4) > +---------+ > | > | (5) > v > +---------+ > | Work C | (6) > +---------+ > | > v > > We have to consider whole context of the worker to build dependencies > with a crosslock e.g. wait_for_commplete(). > > Only thing we have to care here is to make all works e.g. (2), (4) and > (6) independent, because workqueue does _concurrency control_. As I said > last year at the very beginning, for works not applied the control e.g. > max_active == 1, we don't need that isolation. I said, it's a future work. > > It would have been much easier to communicate with each other if you > *tried* to understand my examples like now or you *tried* to give me one > example at least. You didn't even *try*. Only thing I want to ask you > for is to *try* to understand my opinions on conflicts. > > Now, understand what I intended? Still unsufficient? So you worry about max_active==1 ? Or you worry about pool->lock or about the thread setup? I'm still not sure.