-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Paul, first of all: sorry for the late reply.
On 22.12.2012 16:29, Paul Alfille wrote: > Very thoughtful note. > > Let me explore one of your ideas, on polling. > > > On Fri, Dec 21, 2012 at 6:06 PM, Michael Markstaller > <m...@elabnet.de <mailto:m...@elabnet.de>> wrote: > > > And then I thought, if it wouldn't be great for owserver to have > some kind of long-polling API where the client only gets notified > if something interesting (again: iButtons, IO's) has changed > instead of polling every 100ms.. Though I have no idea if/how this > could be implemented.. During the next days I wanted to add some > timestamp-output to debugging to find out where we loose these > 1-3secs but maybe there is an easier way/thought.. > > > The only way owserver could notify you of changes, is indeed to > poll, every so often. > > One method would be to add that function into owserver, as you > suggest. > > Another way would be to create an "owpoll" that would be configured > to poll owserver. 1. The overhead of communicating with owserver is > negligible. (just chain some owservers together to prove this). 2. > owpoll could implement it's own configuration and communication > system. It's not clear how you'd want the signalling to be done. 3. > owpoll could also act as a passthough to owserver to simplify the > client connections. 4. Perhaps owpoll could have some intelligence > about what frequency to poll given items. Let me specify this.. and why.. I agree that the overhead of polling owserver every 100ms (* I don't use owfs/fuse at all, sorry ;)) is negligible.. But there is some, somewhere, owserver eats 25% of my CPU.. The reason behind this is simple and goes back to many (days, weeks) tests done with mobile, battery-driven clients: polling often is very costly: the bill is simply runtime. These tests were with an event-driven system (EIB/KNX) but the basics are the same: the server could run and do&consume what it likes, as long as it doesnt bother clients with irrelevant packets forcing them to wakeup from standby.. The signalling is simple: http://en.wikipedia.org/wiki/Long_polling#Long_polling Simplified; "Don't speak until you have something new for me" ;) Surely, this could be implemented as a sep. "owpoll" or so, this is what I do (around 5 corners) now.. but.. > On the other hand, 1-wire has a assynchronous presence detect mote > for some bus masters that we don't exploit. Because it's hard to do > for serial connections, and any communication on the bus can > interfere with it. I suppose that we could use it on the USB bus. > owlib knows when the bus is idle and so could sense new connections > during that period. (This only works for ibuttons being plugged in, > not new sensor values, those still need polling.) It would be great if we could expose more things there (I don't care if some DIY-stuff works, Ok, well I do but not if it affects stability like accepting DS2490/9490 without an id-chip it's counter-productive IMHO) Really, I never got to understand this "Presence-Pulse" thing in real life, either I didn't understand it or it's not working at all (fully besides owfs!, talking about looking at logicanalyzer and osci now..) Anyway: even if, it would be great but there are only two chips AFAIK that support it at all and I dont have them in the field and they arent what I'd call cheap, so we still have to poll somewhere ;) Finally, the first target is to make the SEARCH_ROM on multiple DS9490 *much* faster, then lower the CPU-load (I just suspect my kind of "hardcore polling" to be *one* of the reasons..) And then, third, it would be nice if owserver could poll itself (or being told to do) and give me just whatever channged ;) best regards, Michael -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with undefined - http://www.enigmail.net/ iEYEARECAAYFAlDebE8ACgkQaWRHV2kMuAKCfgCfTkNKOmQPsNbfZIgxvYeHEOhY MB8AnRazyU0o9qwTnU+K1SHIUzp5SjaH =dL5L -----END PGP SIGNATURE----- ------------------------------------------------------------------------------ Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. SALE $99.99 this month only -- learn more at: http://p.sf.net/sfu/learnmore_122912 _______________________________________________ Owfs-developers mailing list Owfs-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/owfs-developers
