scriptoriumadmin/featurebase
1
0
Fork 0
mirror of https://github.com/featurebasedb/featurebase.git synced 2026-09-12 07:41:02 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

roaring: speed-up intersectionCountArrayBitmap

Browse source 
While looking at benchmarks as a possible go compiler benchmarks.
I've tried some optimizations by hand:
Move len(b.bitmap) load out of the loop.
Remove some type conversions.
Use (x >> off) & 1  to get offs bit, instead of  x & (1 << of)f >> off.

This produces nice speed-up and passes go test roaring.

name                                    old time/op  new time/op  delta
Bitmap_IntersectionCount_ArrayRun-6     2.06µs ± 0%  1.57µs ± 0%  -24.04%  (p=0.000 n=10+9)
Bitmap_IntersectionCount_BitmapRun-6    2.24µs ± 0%  2.24µs ± 0%     ~     (p=0.913 n=10+9)
Bitmap_IntersectionCount_ArrayBitmap-6  2.06µs ± 0%  1.56µs ± 1%  -24.05%  (p=0.000 n=9+10)
This commit is contained in:
Ilya Tocar 2018-02-28 16:41:51 -06:00
parent 280b21b533
commit 2c8d9a5ae0
1 changed files with 4 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
roaring/roaring.go
View file

@ -1907,13 +1907,14 @@ func intersectionCountBitmapRun(a, b *container) (n int) {
}
func intersectionCountArrayBitmap(a, b *container) (n int) {
ln := len(b.bitmap)
for _, val := range a.array {
i := val >> 6
if i >= uint16(len(b.bitmap)) {
i := int(val >> 6)
if i >= ln {
break
}
off := val % 64
n += int((b.bitmap[i] & (1 << off)) >> off)
n += int(b.bitmap[i]>>off) & 1
}
return n
}