John, Adding -C0.005 makes it much better. Using -C0.001 makes it behave more like -N4.
Thanks. This saves my project, as I need to deploy on a single core Atom and was stuck. Mike On Oct 29, 2014, at 5:12 PM, John Lato <jwl...@gmail.com> wrote: > By any chance do the delays get shorter if you run your program with `+RTS > -C0.005` ? If so, I suspect you're having a problem very similar to one that > we had with ghc-7.8 (7.6 too, but it's worse on ghc-7.8 for some reason), > involving possible misbehavior of the thread scheduler. > > On Wed, Oct 29, 2014 at 2:18 PM, Michael Jones <m...@proclivis.com> wrote: > I have a general question about thread behavior in 7.8.3 vs 7.6.X > > I moved from 7.6 to 7.8 and my application behaves very differently. I have > three threads, an application thread that plots data with wxhaskell or sends > it over a network (depends on settings), a thread doing usb bulk writes, and > a thread doing usb bulk reads. Data is moved around with TChan, and TVar is > used for coordination. > > When the application was compiled with 7.6, my stream of usb traffic was > smooth. With 7.8, there are lots of delays where nothing seems to be running. > These delays are up to 40ms, whereas with 7.6 delays were a 1ms or so. > > When I add -N2 or -N4, the 7.8 program runs fine. But on 7.6 it runs fine > without with -N2/4. > > The program is compiled -O2 with profiling. The -N2/4 version uses more > memory, but in both cases with 7.8 and with 7.6 there is no space leak. > > I tired to compile and use -ls so I could take a look with threadscope, but > the application hangs and writes no data to the file. The CPU fans run wild > like it is in an infinite loop. It at least pops an unpainted wxhaskell > window, so it got partially running. > > One of my libraries uses option -fsimpl-tick-factor=200 to get around the > compiler. > > What do I need to know about changes to threading and event logging between > 7.6 and 7.8? Is there some general documentation somewhere that might help? > > I am on Ubuntu 14.04 LTS. I downloaded the 7.8 tool chain tar ball and > installed myself, after removing 7.6 with apt-get. > > Any hints appreciated. > > Mike > > > _______________________________________________ > Glasgow-haskell-users mailing list > Glasgow-haskell-users@haskell.org > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users >
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