On Thu, May 14, 2020 at 9:28 AM <overexcha...@gmail.com> wrote: > I learnt that, > > the reason we have context(`P`) introduced in Goruntime, is that we can > hand them off(it's LRQ of goroutines) to other OS thread(say `M0`), if the > running OS thread(`M1`) needs to block for some reason. > > > [image: Untitled.png] > > > ------------------------------ > > Above, we see a thread(`M1`) giving up its context so that another > thread(`M0`) can run it. The Go scheduler makes sure there are enough > threads to run all contexts(`P1`, `P2`, `P3` etc..). > > > ---------------- > > Above model is `M:N` [threading model]( > https://cs.stackexchange.com/questions/1074/what-is-the-purpose-of-mn-hybrid-threading), > where each OS thread(`M1`) running on CPU core(`C`) assigned a context(`P`) > having `K` goroutines in it's LRQ. > > vis-a-vis > > `1:1` threading model, where each core(`C`) has one OS thread(`M`). > `pthread_create()`. > > Comparing above two threading models, context switching of go-routines(in > `M:N` threading model) is much faster than context-switching of OS > threads(in `1:1` threading model) > > -------------------------- > > To understand the purpose of context(`P`), > > what is the advantage of handing off context(`P1`) to other thread(say > `M2`) running on core(`C2`)? > > Is the advantage about efficiency in re-using cache lines(L1/L2) on core > `C2`, for the related set of goroutines sitting in LRQ of context(`P1`)? >
What do you mean when you write context(`P`)? By that do you simply mean what the runtime package calls a P? A P is a logical processor; see the long comment at the top of runtime/proc.go. Ian -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAOyqgcXkVNR1%2B19zUCCD-p%3DS4epb7ysV4ZEnJmJ7XAcVi3U_-g%40mail.gmail.com.
