Mike Gerwitz

Activist for User Freedom

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authorMike Gerwitz <mike.gerwitz@ryansg.com>2021-08-18 14:18:24 -0400
committerMike Gerwitz <mike.gerwitz@ryansg.com>2021-08-18 14:23:03 -0400
commitfc235b7eccc315cb0841534c3ef636386c5cd238 (patch)
tree0c3cb2c7dcf69fbf2ce126da3272989a14dcf467 /tamer/Cargo.lock
parent1cdb3fbbc52d5abe8456392995c63d2f46113127 (diff)
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tamer: memchr benches
This adds benchmarking for the memchr crate. It is used primarily by quick-xml at the moment, but the question is whether to rely on it for certain operations for XIR. The benchmarking on an Intel Xeon system shows that memchr and Rust's contains() perform very similarly on small inputs, matching against a single character, and so Rust's built-in should be preferred in that case so that we're using APIs that are familiar to most people. When larger inputs are compared against, there's a greater benefit (a little under ~2x). When comparing against two characters, they are again very close. But look at when we compare two characters against _multiple_ inputs: running 24 tests test large_str::one::memchr_early_match ... bench: 4,938 ns/iter (+/- 124) test large_str::one::memchr_late_match ... bench: 81,807 ns/iter (+/- 1,153) test large_str::one::memchr_non_match ... bench: 82,074 ns/iter (+/- 1,062) test large_str::one::rust_contains_one_byte_early_match ... bench: 9,425 ns/iter (+/- 167) test large_str::one::rust_contains_one_byte_late_match ... bench: 123,685 ns/iter (+/- 3,728) test large_str::one::rust_contains_one_byte_non_match ... bench: 123,117 ns/iter (+/- 2,200) test large_str::one::rust_contains_one_char_early_match ... bench: 9,561 ns/iter (+/- 507) test large_str::one::rust_contains_one_char_late_match ... bench: 123,929 ns/iter (+/- 2,377) test large_str::one::rust_contains_one_char_non_match ... bench: 122,989 ns/iter (+/- 2,788) test large_str::two::memchr2_early_match ... bench: 5,704 ns/iter (+/- 91) test large_str::two::memchr2_late_match ... bench: 89,194 ns/iter (+/- 8,546) test large_str::two::memchr2_non_match ... bench: 85,649 ns/iter (+/- 3,879) test large_str::two::rust_contains_two_char_early_match ... bench: 66,785 ns/iter (+/- 3,385) test large_str::two::rust_contains_two_char_late_match ... bench: 2,148,064 ns/iter (+/- 21,812) test large_str::two::rust_contains_two_char_non_match ... bench: 2,322,082 ns/iter (+/- 22,947) test small_str::one::memchr_mid_match ... bench: 4,737 ns/iter (+/- 842) test small_str::one::memchr_non_match ... bench: 5,160 ns/iter (+/- 62) test small_str::one::rust_contains_one_byte_non_match ... bench: 3,930 ns/iter (+/- 35) test small_str::one::rust_contains_one_char_mid_match ... bench: 3,677 ns/iter (+/- 618) test small_str::one::rust_contains_one_char_non_match ... bench: 5,415 ns/iter (+/- 221) test small_str::two::memchr2_mid_match ... bench: 5,488 ns/iter (+/- 888) test small_str::two::memchr2_non_match ... bench: 6,788 ns/iter (+/- 134) test small_str::two::rust_contains_two_char_mid_match ... bench: 6,203 ns/iter (+/- 170) test small_str::two::rust_contains_two_char_non_match ... bench: 7,853 ns/iter (+/- 713) Yikes. With that said, we won't be comparing against such large inputs short-term. The larger strings (fragments) are copied verbatim, and not compared against---but they _were_ prior to the previous commit that stopped unencoding and re-encoding. So: Rust built-ins for inputs that are expected to be small.
Diffstat (limited to 'tamer/Cargo.lock')
-rw-r--r--tamer/Cargo.lock1
1 files changed, 1 insertions, 0 deletions
diff --git a/tamer/Cargo.lock b/tamer/Cargo.lock
index bcb82a3..4eacee0 100644
--- a/tamer/Cargo.lock
+++ b/tamer/Cargo.lock
@@ -302,6 +302,7 @@ dependencies = [
"fxhash",
"getopts",
"lazy_static",
+ "memchr",
"petgraph",
"petgraph-graphml",
"predicates",