At Thu, 16 Jan 2014 22:06:18 +0800,
Liu Yuan wrote:
>
> On Thu, Jan 16, 2014 at 10:58:35PM +0900, MORITA Kazutaka wrote:
> > At Thu, 16 Jan 2014 16:32:42 +0800,
> > Liu Yuan wrote:
> > >
> > > Since current code works well, do we really need to introduce prioritized event
> > > loop which need some overhead of sorting events?
> > >
> > > For now with this patch set, the only benefit is that it looks more 'beautiful'
> > > that we have complete reg/unreg for worker threads, which isn't must for making
> > > code correct nor run faster.
> > >
> > > The downside is obvious, that 1) reg/unreg in worker is worsen a bit 2) event loop
> > > is affected negatively by sorting overhead. We don't get pratical benefits.
> > >
> > > I want to get other developer's opinion.
> >
> > To be honest, I don't like both.
> >
> > The current code assumes that register_event() must be called by at
> > most one thread. However, we don't do any check about it in
> > register_event(). I don't think Hitoshi's approach is a good one,
> > too. It adds many codes and complexity.
> >
> > Do we really need exec_local_req_async() and the short event
> > framework? The use case of exec_local_req_async() is:
> >
> > iocb = local_req_init();
> >
> > loop:
> > ...
> > exec_local_req_async(req, iocb);
> > ...
> >
> > ret = local_req_wait(iocb);
> >
> > However, we can do the similar thing with a work queue:
> >
> > wq = create_work_queue();
> >
> > loop:
> > ...
> > work.fn = do_work;
> > work.done = do_main;
> > queue_work(wq, &work);
> > ...
> >
> > while (nr--) {
> > eventfd_read(efd);
> > }
> >
> > ...
> >
> > void do_work()
> > {
> > exec_local_req(req);
> > }
> >
> > void do_main()
> > {
> > eventfd_write(efd);
> > }
> >
> >
> > If we can move forward without introducing an additional framework
> > like a short event, it looks much better way to me.
> >
>
> Looks feasible to me (looks the same as that in object cache), but can you
> provide the complete patch? I hope we can get a nice API to do async request
> without touching low level work queue and eventfd stuff.
Sure, I'll do it tomorrow.
Thanks,
Kazutaka
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