What are the reason for the performance improvement cause by alloc data of different sizes to adjacent memory addresses?

[qiulaidongfeng]

I recently added a new API (AllocSoonUse) to the https://gitee.com/qiulaidongfeng/arena I wrote (copy in https://github.com/qiulaidongfeng/arena)

This API allocdata to adjacent []byte, and the length can be set.

I use this benchmark code : https://go.dev/play/p/nAGveraT5_h

benchmark Brief description, use AllocSoonUse and new to allocate some data of different sizes that does not contain Pointers and use it soon after allocation.

I use `go test -bench=. -count=10 -benchtime=2s > new.txt && benchstat new.txt`  got this result

         │   new.txt   │
         │   sec/op    │
NoStd-16   207.4µ ± 4%
Std-16     245.0µ ± 1%
geomean    225.4µ

It appears that using AllocSoonUse takes 15.34% less time than using new in some scenarios.

I initially speculated that the reason for the performance improvement was the change in cache hit rate.

But using this benchmark https://go.dev/play/p/SCNMV6I9GWC and `go test -bench=. -count=10 -benchtime=2s > new.txt && benchstat new.txt`  got this result

         │   new.txt   │
         │   sec/op    │
NoStd-16   206.6µ ± 3%
Std-16     236.0µ ± 2%
geomean    220.9µ

It appears that there is still a 12.45% performance gap after commenting out the access code to allocated memory to reduce the access to memory.

I want to get the performance gap so the reason.

The possibility has been ruled out, AllocSoonUse  allows free memory in a way that allows for immediate reuse  , but I did not enable this opt-in.