Hash VecDeque in its slice parts #31224
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(rust_highfive has picked a reviewer for you, use r? to override) |
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Benchmark code: https://gist.github.com/bluss/a021d1a71b2709dbf724 |
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@_@ DAT PERF 💯 |
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Can you add a test that verifies that different splits yield the same hash? Something like pushpushpush == pushpushpoppushpush |
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Also: dang! Should we be doing this for eq/ord, etc? |
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I'm working on this for eq. We should absolutely use slices everywhere we can (llvm likes them, see #30805). A test to verify same hash, same eq for different splits sounds good. Will do. |
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I added a test! |
| for elt in &mut ring { | ||
| *elt -= 1; | ||
| } | ||
| ring.push_back(first + len - 1); |
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first == 0, so this is just len - 1?
Use .as_slices() for a more efficient code path in VecDeque's Hash impl. This still hashes the elements in the same order. Before/after timing of VecDeque hashing 1024 elements of u8 and u64 shows that the vecdeque now can match the Vec (test_hashing_vec_of_u64 is the Vec run). before test test_hashing_u64 ... bench: 14,031 ns/iter (+/- 236) = 583 MB/s test test_hashing_u8 ... bench: 7,887 ns/iter (+/- 65) = 129 MB/s test test_hashing_vec_of_u64 ... bench: 6,578 ns/iter (+/- 76) = 1245 MB/s after running 5 tests test test_hashing_u64 ... bench: 6,495 ns/iter (+/- 52) = 1261 MB/s test test_hashing_u8 ... bench: 851 ns/iter (+/- 16) = 1203 MB/s test test_hashing_vec_of_u64 ... bench: 6,499 ns/iter (+/- 59) = 1260 MB/s
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@bors r+ |
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📌 Commit d3174ce has been approved by |
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Thanks for the feedback Gankro! Together we will hash these bytes, faster than ever. |
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Hash VecDeque in its slice parts Use .as_slices() for a more efficient code path in VecDeque's Hash impl. This still hashes the elements in the same order. Before/after timing of VecDeque hashing 1024 elements of u8 and u64 shows that the vecdeque now can match the Vec (test_hashing_vec_of_u64 is the Vec run). ``` before test test_hashing_u64 ... bench: 14,031 ns/iter (+/- 236) = 583 MB/s test test_hashing_u8 ... bench: 7,887 ns/iter (+/- 65) = 129 MB/s test test_hashing_vec_of_u64 ... bench: 6,578 ns/iter (+/- 76) = 1245 MB/s after running 5 tests test test_hashing_u64 ... bench: 6,495 ns/iter (+/- 52) = 1261 MB/s test test_hashing_u8 ... bench: 851 ns/iter (+/- 16) = 1203 MB/s test test_hashing_vec_of_u64 ... bench: 6,499 ns/iter (+/- 59) = 1260 MB/s ```
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Hash VecDeque in its slice parts
Use .as_slices() for a more efficient code path in VecDeque's Hash impl.
This still hashes the elements in the same order.
Before/after timing of VecDeque hashing 1024 elements of u8 and
u64 shows that the vecdeque now can match the Vec
(test_hashing_vec_of_u64 is the Vec run).