On Thu, Jul 1, 2021 at 2:35 PM tapi...@gmail.com <tapir....@gmail.com> wrote:
> It is not rare a function will use 10M+ stack. > FWIW, it being rare is one side of the equation. The other side is how large the overhead is - and ISTM that overhead is ~2x. That's not nothing, but it's also not extreme, for something that takes very little time. The other thing, of course, is that *there is code* to avoid that overhead - it just isn't triggered by your example, for some reason (as I said, I could imagine it has something to do with running on the system stack). It's not unreasonable to assume that *in general*, a function using a 10M+ will use the more efficient growth path. So that even if it's not uncommon to use a large stack, it *is* uncommon for that to be a problem. I genuinely don't know. For that, I would have to know *why* your example isn't more efficient. I don't care enough to find out. But it might be completely reasonable behavior. > > On Thursday, July 1, 2021 at 4:13:40 AM UTC-4 Volker Dobler wrote: > >> Note that the compiler should generate efficient code for >> common, typical, real-world code. Optimising the compiler >> to generate the most efficient code for pathological code >> can be a waste of time, both for the compiler writers and >> for the users waiting longer for their "normal" code to be >> compiled. Nevertheless the compiler should emit "decent" >> code for pathological cases. The quadratic stack growth >> seems decent to me. >> >> V. >> >> On Thursday, 1 July 2021 at 03:03:37 UTC+2 tapi...@gmail.com wrote: >> >>> On Wednesday, June 30, 2021 at 8:46:19 PM UTC-4 >>> axel.wa...@googlemail.com wrote: >>> >>>> On Thu, Jul 1, 2021 at 2:34 AM tapi...@gmail.com <tapi...@gmail.com> >>>> wrote: >>>> >>>>> >>>>> >>>>> On Wednesday, June 30, 2021 at 11:56:45 AM UTC-4 Brian Candler wrote: >>>>> >>>>>> So I think what you're asking is, "under what scenario does the code >>>>>> in L1066-1069 >>>>>> <https://github.com/golang/go/blob/d19a53338fa6272b4fe9c39d66812a79e1464cd2/src/runtime/stack.go#L1065-L1070> >>>>>> get run?" - is that right? >>>>> >>>>> >>>>> Almost true. >>>>> >>>>> Whether or not it should run, growing the stack from 2048 to 512M in >>>>> 18+ steps looks not right. >>>>> >>>> >>>> Why? 2048 • 2^18 = 2^11 • 2^18 = 2^29 = 536870912. >>>> Seems like exactly the expected result. >>>> >>> >>> It looks each step calls copystack once. >>> Isn't one step more efficient? >>> >>> >>>> >>>> >>>>> >>>>> >>>>>> >>>>>> On Wednesday, 30 June 2021 at 14:21:21 UTC+1 tapi...@gmail.com wrote: >>>>>> >>>>>>> Sorry, I post the wrong anchor. It is line 1068: >>>>>>> https://github.com/golang/go/blob/d19a53338fa6272b4fe9c39d66812a79e1464cd2/src/runtime/stack.go#L1068 >>>>>>> >>>>>>> On Wednesday, June 30, 2021 at 5:08:30 AM UTC-4 Brian Candler wrote: >>>>>>> >>>>>>>> On Wednesday, 30 June 2021 at 08:25:59 UTC+1 tapi...@gmail.com >>>>>>>> wrote: >>>>>>>> >>>>>>>>> >>>>>>>>> It looks this line >>>>>>>>> https://github.com/golang/go/blob/master/src/runtime/stack.go#L1078 >>>>>>>>> never gets executed. >>>>>>>>> >>>>>>>>> >>>>>>>> Can you quote the line you're referring to? Line numbers can shift >>>>>>>> up and down as commits are made to the master branch. Right now, L1078 >>>>>>>> is a >>>>>>>> blank line. >>>>>>>> >>>>>>> -- >>>>> >>>> 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...@googlegroups.com. >>>>> >>>> To view this discussion on the web visit >>>>> https://groups.google.com/d/msgid/golang-nuts/5fab5a6e-5dd5-4df2-8b31-4a51aa825f92n%40googlegroups.com >>>>> <https://groups.google.com/d/msgid/golang-nuts/5fab5a6e-5dd5-4df2-8b31-4a51aa825f92n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>> . >>>>> >>>> -- > 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/9e869b98-f3e0-4bfd-8a24-56c9a8dea8a4n%40googlegroups.com > <https://groups.google.com/d/msgid/golang-nuts/9e869b98-f3e0-4bfd-8a24-56c9a8dea8a4n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- 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/CAEkBMfG%3DPzP_b7xW7u6jhxP6EFbZ7y43Ckt-wFyW5t3%2BLZpiyQ%40mail.gmail.com.
