On Tue, 29 Apr 2025 15:10:10 GMT, fabioromano1 <[email protected]> wrote:
>> This PR optimizes `BigInteger.pow(int)` method. The primary enhancement in
>> `pow()` is not concerned most on execution time, but rather in memory
>> optimization, because the PR implementation does the "shift of the exponent"
>> squaring the result rather than the base, so the base is not squared like in
>> the current implementation, and this permits to save about half of the
>> memory.
>
> fabioromano1 has updated the pull request incrementally with two additional
> commits since the last revision:
>
> - Adjust the type of operand
> - Use a more loose formula to do range check
>
> Use a more loose formula to do range check, in order not to exclude a
> priori values that may be inside the supported range
I must have screwed up something in my previous benchmarks, probably when
copying the master branch (current) `BigInteger` into the PR branch for the
"before" figures.
Here's indeed a more favorable picture (but certainly not a 50% enhancement in
allocation rate).
I obtain comparable results with more iterations (`make test
TEST="micro:java.math.BigIntegerPow" MICRO="WARMUP_ITER=3;ITER=3;OPTIONS=-prof
gc"`).
I'll delete my previous misleading results.
Sorry for the noise.
macOS 15.4.1 / M1 Pro / 32 GiB / java 25-internal
_before_
Benchmark Mode Cnt Score
Error Units
BigIntegerPow.testPowL avgt 3 7828857180.333 ±
723831405.464 ns/op
BigIntegerPow.testPowL:gc.alloc.rate avgt 3 4766.633 ±
440.607 MB/sec
BigIntegerPow.testPowL:gc.alloc.rate.norm avgt 3 39130646080.000 ±
0.001 B/op
BigIntegerPow.testPowL:gc.count avgt 3 260.000
counts
BigIntegerPow.testPowL:gc.time avgt 3 190.000
ms
BigIntegerPow.testPowM avgt 3 7784905013.667 ±
751070238.685 ns/op
BigIntegerPow.testPowM:gc.alloc.rate avgt 3 4737.671 ±
455.843 MB/sec
BigIntegerPow.testPowM:gc.alloc.rate.norm avgt 3 38674111834.667 ±
337.057 B/op
BigIntegerPow.testPowM:gc.count avgt 3 257.000
counts
BigIntegerPow.testPowM:gc.time avgt 3 192.000
ms
BigIntegerPow.testPowS avgt 3 7615946041.333 ±
505408224.968 ns/op
BigIntegerPow.testPowS:gc.alloc.rate avgt 3 4622.726 ±
306.660 MB/sec
BigIntegerPow.testPowS:gc.alloc.rate.norm avgt 3 36917399656.000 ±
0.001 B/op
BigIntegerPow.testPowS:gc.count avgt 3 246.000
counts
BigIntegerPow.testPowS:gc.time avgt 3 184.000
ms
BigIntegerPow.testPowXL avgt 3 7806063305.667 ±
841981680.300 ns/op
BigIntegerPow.testPowXL:gc.alloc.rate avgt 3 4795.153 ±
515.480 MB/sec
BigIntegerPow.testPowXL:gc.alloc.rate.norm avgt 3 39249581269.333 ±
337.057 B/op
BigIntegerPow.testPowXL:gc.count avgt 3 261.000
counts
BigIntegerPow.testPowXL:gc.time avgt 3 194.000
ms
BigIntegerPow.testPowXS avgt 3 6613315027.667 ±
330610647.532 ns/op
BigIntegerPow.testPowXS:gc.alloc.rate avgt 3 4254.182 ±
212.492 MB/sec
BigIntegerPow.testPowXS:gc.alloc.rate.norm avgt 3 29501518834.667 ±
337.057 B/op
BigIntegerPow.testPowXS:gc.count avgt 3 197.000
counts
BigIntegerPow.testPowXS:gc.time avgt 3 147.000
ms
_after_
Benchmark Mode Cnt Score
Error Units
BigIntegerPow.testPowL avgt 3 7366544708.333 ±
829671998.680 ns/op
BigIntegerPow.testPowL:gc.alloc.rate avgt 3 4018.527 ±
452.726 MB/sec
BigIntegerPow.testPowL:gc.alloc.rate.norm avgt 3 31040625690.667 ±
337.057 B/op
BigIntegerPow.testPowL:gc.count avgt 3 201.000
counts
BigIntegerPow.testPowL:gc.time avgt 3 138.000
ms
BigIntegerPow.testPowM avgt 3 5185182639.000 ±
115159325.868 ns/op
BigIntegerPow.testPowM:gc.alloc.rate avgt 3 3784.654 ±
158.695 MB/sec
BigIntegerPow.testPowM:gc.alloc.rate.norm avgt 3 20578167389.333 ±
439891534.193 B/op
BigIntegerPow.testPowM:gc.count avgt 3 135.000
counts
BigIntegerPow.testPowM:gc.time avgt 3 89.000
ms
BigIntegerPow.testPowS avgt 3 5129524208.333 ±
622597661.429 ns/op
BigIntegerPow.testPowS:gc.alloc.rate avgt 3 3807.115 ±
460.287 MB/sec
BigIntegerPow.testPowS:gc.alloc.rate.norm avgt 3 20477396202.667 ±
337.057 B/op
BigIntegerPow.testPowS:gc.count avgt 3 135.000
counts
BigIntegerPow.testPowS:gc.time avgt 3 90.000
ms
BigIntegerPow.testPowXL avgt 3 8098242069.667 ±
905979832.443 ns/op
BigIntegerPow.testPowXL:gc.alloc.rate avgt 3 4134.655 ±
462.498 MB/sec
BigIntegerPow.testPowXL:gc.alloc.rate.norm avgt 3 35109921325.333 ±
337.057 B/op
BigIntegerPow.testPowXL:gc.count avgt 3 231.000
counts
BigIntegerPow.testPowXL:gc.time avgt 3 159.000
ms
BigIntegerPow.testPowXS avgt 3 4587145069.333 ±
537879394.284 ns/op
BigIntegerPow.testPowXS:gc.alloc.rate avgt 3 3916.668 ±
458.061 MB/sec
BigIntegerPow.testPowXS:gc.alloc.rate.norm avgt 3 18839312829.333 ±
337.057 B/op
BigIntegerPow.testPowXS:gc.count avgt 3 123.000
counts
BigIntegerPow.testPowXS:gc.time avgt 3 82.000
ms
-------------
PR Comment: https://git.openjdk.org/jdk/pull/24690#issuecomment-2839600648
