optimize the medium algorithm
#223
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Benchmark 1 (31 runs): ./compress-baseline 3 rs silesia-small.tar measurement mean ± σ min … max outliers delta wall_time 164ms ± 3.09ms 161ms … 178ms 2 ( 6%) 0% peak_rss 24.7MB ± 52.6KB 24.6MB … 24.8MB 6 (19%) 0% cpu_cycles 666M ± 12.7M 657M … 725M 2 ( 6%) 0% instructions 1.71G ± 278 1.71G … 1.71G 0 ( 0%) 0% cache_references 43.7M ± 474K 43.1M … 45.1M 0 ( 0%) 0% cache_misses 1.17M ± 276K 862K … 2.25M 1 ( 3%) 0% branch_misses 7.78M ± 8.65K 7.77M … 7.81M 1 ( 3%) 0% Benchmark 2 (34 runs): target/release/examples/blogpost-compress 3 rs silesia-small.tar measurement mean ± σ min … max outliers delta wall_time 150ms ± 4.69ms 148ms … 175ms 2 ( 6%) ⚡- 8.1% ± 1.2% peak_rss 24.7MB ± 65.5KB 24.6MB … 24.8MB 0 ( 0%) - 0.2% ± 0.1% cpu_cycles 650M ± 19.1M 640M … 748M 2 ( 6%) ⚡- 2.3% ± 1.2% instructions 1.66G ± 298 1.66G … 1.66G 0 ( 0%) ⚡- 2.9% ± 0.0% cache_references 43.8M ± 451K 43.0M … 44.9M 0 ( 0%) + 0.0% ± 0.5% cache_misses 1.09M ± 267K 758K … 1.86M 1 ( 3%) - 6.9% ± 11.5% branch_misses 7.80M ± 12.9K 7.78M … 7.84M 3 ( 9%) + 0.2% ± 0.1%
reduces instruction count, does not yet improve performance
Benchmark 2 (36 runs): target/release/examples/blogpost-compress 3 rs silesia-small.tar measurement mean ± σ min … max outliers delta wall_time 141ms ± 1.98ms 139ms … 151ms 1 ( 3%) ⚡- 3.8% ± 1.2% peak_rss 24.7MB ± 71.1KB 24.5MB … 24.8MB 0 ( 0%) - 0.1% ± 0.1% cpu_cycles 626M ± 7.96M 620M … 667M 1 ( 3%) ⚡- 3.7% ± 1.0% instructions 1.60G ± 308 1.60G … 1.60G 0 ( 0%) ⚡- 3.7% ± 0.0% cache_references 43.9M ± 494K 43.2M … 45.0M 0 ( 0%) + 0.3% ± 0.6% cache_misses 1.07M ± 259K 769K … 1.85M 1 ( 3%) + 5.8% ± 13.3% branch_misses 7.79M ± 4.52K 7.78M … 7.80M 2 ( 6%) - 0.1% ± 0.0%
Codecov ReportAll modified and coverable lines are covered by tests ✅
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| filled: 0, | ||
| initialized: 0, | ||
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| buf.fill(MaybeUninit::new(0)); |
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Allocators often have an option to directly allocate pre-zeroed memory. How hard would it be to make use of this when not being passed a custom allocator to use?
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it's possible, but a bit cursed maybe? you'd have to check that the allocator is one you know, and can then special-case to use calloc or similar.
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Or maybe you can add a field to Allocator and keep it either None or a function that forwards to the regular alloc function in the code that accepts an allocator from the C side and turns it into an Allocator instance. This way you did use the zeroed allocator method if the C side didn't specify an allocator to use.
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Opened #224 against this PR to fix CI. |
much better than before
but still a ways to go
but, most of these changes are actually beneficial for all compression levels, so at the higher levels we're doing really well