At Tue, 17 Dec 2013 15:41:31 +0800, Liu Yuan wrote: > > On Tue, Dec 17, 2013 at 04:33:58PM +0900, Hitoshi Mitake wrote: > > At Tue, 17 Dec 2013 15:11:30 +0800, > > Liu Yuan wrote: > > > > > > > > From the perspective of > > > > maintenance and debugging, I cannot agree with this patch. Adding a > > > > new workqueue for register/unregister in the main loop will save lots > > > > of our time in the future. > > > > > > I think this approach will not work for async request handling, e.g, > > > > > > + uatomic_inc(&iocb->count); > > > + req->iocb = iocb; > > > + register_event(req->local_req_efd, local_req_async_handler, req); > > > + submit_local_request(req); > > > > > > I have to register the event before sumit_local_request(). > > > > > > If I don't and put registeration in a delegated thread, suppose that is > > > called > > > after request is already handled. So I'll miss the notification that the > > > request > > > is done and local_req_async_handler will never be called. > > > > > > How do we handle above problem if we use your approach? > > > > > > If we take performance into account, we can't do it in your approch > > > either. > > > Suppose we will issue 1000 requests in a async mode, we can't affort to > > > be trapped > > > to main thread to register event for every request. > > > > I have an internal under construction change for parameterizing event > > loop. Current event loop mechanism has a limitation that we can have only > > one > > event loop per process. The change is for removing this limitation. > > > > Making dedicated event loop which can be managed by worker threads would be > > helpful for your problem. > > This is a more ratical change compared to my patch and I think it really needs > discusstion to do it. > > > The change is originally intended for solving the problem that dog can use > > too > > many memory area in some case (e.g. checking large VDIs) > > > > I can't figure out why memory consumption is related to event loop. If you > have > mutliple loop, it doesn't mean will cost less memory for threads. >
Current dog uses a way like below: 1. produce every work 2. reduce every work with work_queue_wait() This way clearly consumes too many memory space. For example, generating every work for checking hypervolume VDI would consume too large area. So we need a mechanism that limiting a number of work produced at a given point in time and reduce them by the main loop as needed. Thanks, Hitoshi -- sheepdog mailing list sheepdog@lists.wpkg.org http://lists.wpkg.org/mailman/listinfo/sheepdog
