Oops, sorry, only just now seen this. It seems my overly aggressive filters couldn't decide where to put the email :)
I do agree to some extend with this. I'd prefer if I made a mistake for my system not to hang. The one downside to this default though is that you can't just hand a program over to user and have it run at full capabilities. If it possible to set this from inside a program? My guess is no, since by the time you get to main the rts is already initialized? Would a useful alternative be to provide a compile flag that would change the default? e.g. opt-in? Since now there is a small burden on the end user. Cheers, Tamar On Sat, Oct 8, 2016 at 5:55 PM, Ben Gamari <b...@well-typed.com> wrote: > loneti...@gmail.com writes: > > > Hi All, > > > > A user on https://ghc.haskell.org/trac/ghc/ticket/11054 has asked why > > -N -qa isn’t the default for -threaded. > > > I'm not sure that scheduling on all of the cores on the user's machine by > default is a good idea, especially given that our users have > learned to expect the existing default. Enabling affinity by default > seems reasonable if we have evidence that it helps the majority of > applications, but we would first need to introduce an additional > flag to disable it. > > In general I think -N1 is a reasonable default as it acknowledges the > fact that deploying parallelism is not something that can be done > blindly in many (most?) applications. To make effective use of > parallelism the user needs to understand their hardware, their > application, and its interaction with the runtime system and configure > the RTS appropriately. > > Of course, this is just my two-cents. > > Cheers, > > - Ben >
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