Did I do anything wrong, the cache hint ratio decrease linearly, is it an expected result? I thought the cache hint ratio would have a significant drop:
[image: chart.png] Raw data: #goroutines cache-references cache-misses hint/(hint+miss) 2400 697103572 17641686 0.9753175194 3200 798160789 54169784 0.9364451004 3360 1387972473 148415678 0.9033996208 3600 1824541062 272166355 0.8701934506 4000 2053779401 393586501 0.8391795437 4800 1885622275 461872899 0.8032486268 On Monday, August 26, 2019 at 9:26:05 PM UTC+2, Robert Engels wrote: > > You can run the process under 'perf' and monitor the cpu cache hit/miss > ratio. > > -----Original Message----- > From: changkun > Sent: Aug 26, 2019 2:23 PM > To: golang-nuts > Subject: Re: [go-nuts] sync.Mutex encounter large performance drop when > goroutine contention more than 3400 > > Your cache theory is very reasonable, but this was clear in the beginning > post: "before or after the massive increase, performance drops linearly". > Your hypothesis is reasonable, but how can you prove your hypothesis? By > host machine cache usage monitoring? > Matching of a concept is still not persuasive. > > On Monday, August 26, 2019 at 8:08:27 PM UTC+2, Robert Engels wrote: >> >> Which is what I would expect - once the number of routines exhaust the >> cache, it will take the next level (or never since its main memory) to see >> an massive increase in time. 4800 is 30% slower than 3600 - so it is >> increasing linearly with the number of Go routines. >> >> >> -----Original Message----- >> From: changkun >> Sent: Aug 26, 2019 11:49 AM >> To: golang-nuts >> Subject: Re: [go-nuts] sync.Mutex encounter large performance drop when >> goroutine contention more than 3400 >> >> According to your formula let's sample three points: >> >> 2400 goroutines: 2.508s/(50000000*2400) = 2.09 × 10^-11 s >> 3600 goroutines: 12.219s/(50000000*3600) = 6.78833333 × 10-11 seconds >> 4800 goroutines: 16.020s/(50000000*4800) = 6.67500 × 10^-11 s >> >> One can observe that 3600 and 4800 mostly equal to each other, but they >> both three times slower than 2400. >> >> goos: linux >> goarch: amd64 >> BenchmarkMutexWrite/goroutines-2400-8 50000000 >> 46.5 ns/op >> PASS >> ok _/home/changkun/dev/tests 2.508s >> >> goos: linux >> goarch: amd64 >> BenchmarkMutexWrite/goroutines-3600-8 50000000 >> 240 ns/op >> PASS >> ok _/home/changkun/dev/tests 12.219s >> >> goos: linux >> goarch: amd64 >> BenchmarkMutexWrite/goroutines-4800-8 50000000 >> 317 ns/op >> PASS >> ok _/home/changkun/dev/tests 16.020s >> >> >> -- >> 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 golan...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/golang-nuts/6dd6ec66-b0cc-4c8e-a341-94bff187214f%40googlegroups.com >> >> <https://groups.google.com/d/msgid/golang-nuts/6dd6ec66-b0cc-4c8e-a341-94bff187214f%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 golan...@googlegroups.com <javascript:>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/495e22e8-4a5f-4a1d-88f8-59ff2b0a4006%40googlegroups.com > > <https://groups.google.com/d/msgid/golang-nuts/495e22e8-4a5f-4a1d-88f8-59ff2b0a4006%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/0c2b4dc1-3774-4fe6-9cd6-a841dd7265c4%40googlegroups.com.
