diff options
| author | David Chase <drchase@google.com> | 2023-01-13 16:12:47 -0500 |
|---|---|---|
| committer | David Chase <drchase@google.com> | 2023-01-23 15:51:32 +0000 |
| commit | e22bd2348c8e3bfdf12197d0b0e194b66bbf5a36 (patch) | |
| tree | 0c61869dae136d804b1e82091fc562cde4bf7efe /src/runtime/map.go | |
| parent | e2fe35363d070bf37326d04ed28964e6ba3892da (diff) | |
| download | go-e22bd2348c8e3bfdf12197d0b0e194b66bbf5a36.tar.xz | |
internal/abi,runtime: refactor map constants into one place
Previously TryBot-tested with bucket bits = 4.
Also tested locally with bucket bits = 5.
This makes it much easier to change the size of map
buckets, and hopefully provides pointers to all the
code that in some way depends on details of map layout.
Change-Id: I9f6669d1eadd02f182d0bc3f959dc5f385fa1683
Reviewed-on: https://go-review.googlesource.com/c/go/+/462115
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Austin Clements <austin@google.com>
Diffstat (limited to 'src/runtime/map.go')
| -rw-r--r-- | src/runtime/map.go | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/src/runtime/map.go b/src/runtime/map.go index f546ce8609..6179c1e371 100644 --- a/src/runtime/map.go +++ b/src/runtime/map.go @@ -63,20 +63,21 @@ import ( const ( // Maximum number of key/elem pairs a bucket can hold. - bucketCntBits = 3 - bucketCnt = 1 << bucketCntBits + bucketCntBits = abi.MapBucketCountBits + bucketCnt = abi.MapBucketCount - // Maximum average load of a bucket that triggers growth is 6.5. + // Maximum average load of a bucket that triggers growth is bucketCnt*13/16 (about 80% full) + // Because of minimum alignment rules, bucketCnt is known to be at least 8. // Represent as loadFactorNum/loadFactorDen, to allow integer math. - loadFactorNum = 13 loadFactorDen = 2 + loadFactorNum = (bucketCnt * 13 / 16) * loadFactorDen // Maximum key or elem size to keep inline (instead of mallocing per element). // Must fit in a uint8. // Fast versions cannot handle big elems - the cutoff size for // fast versions in cmd/compile/internal/gc/walk.go must be at most this elem. - maxKeySize = 128 - maxElemSize = 128 + maxKeySize = abi.MapMaxKeyBytes + maxElemSize = abi.MapMaxElemBytes // data offset should be the size of the bmap struct, but needs to be // aligned correctly. For amd64p32 this means 64-bit alignment |