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Commit 1f93d710 authored by Sebastian Pop's avatar Sebastian Pop
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use std::hash instead of hashing byte by byte

This patch uses libcxx's string_view hashing.  The performance is better than the
current implementation, and almost the same as for the hashing implementation amended
by the patch in https://android-review.googlesource.com/404742

The following experiments were conducted on a HiKey aarch64 A53.

No changes:
$ adb push out/target/product/hikey/data/benchmarktest64/ziparchive-benchmarks /data
$ adb shell /data/ziparchive-benchmarks --benchmark_repetitions=5
-----------------------------------------------------------------
Benchmark                          Time           CPU Iterations
-----------------------------------------------------------------
FindEntry_no_match          82279629 ns   81759676 ns          9
FindEntry_no_match          81648056 ns   81627431 ns          9
FindEntry_no_match          81384074 ns   81369057 ns          9
FindEntry_no_match          89618889 ns   82437755 ns          9
FindEntry_no_match          81811389 ns   81785261 ns          9
FindEntry_no_match_mean     83348407 ns   81795836 ns          9
FindEntry_no_match_stddev    3520421 ns     394962 ns          0
Iterate_all_files          137622000 ns  137589032 ns          5
Iterate_all_files          139666333 ns  138409469 ns          5
Iterate_all_files          150070000 ns  140883697 ns          5
Iterate_all_files          138600667 ns  138540646 ns          5
Iterate_all_files          137599833 ns  137567438 ns          5
Iterate_all_files_mean     140711767 ns  138598056 ns          5
Iterate_all_files_stddev     5299929 ns    1354928 ns          0

$ cd system/core/libziparchive
$ git fetch https://android.googlesource.com/platform/system/core refs/changes/42/404742/7 && git cherry-pick FETCH_HEAD
$ mma
$ cd -
$ adb push out/target/product/hikey/data/benchmarktest64/ziparchive-benchmarks /data
$ adb shell /data/ziparchive-benchmarks --benchmark_repetitions=5
-----------------------------------------------------------------
Benchmark                          Time           CPU Iterations
-----------------------------------------------------------------
FindEntry_no_match          53302756 ns   53291178 ns         13
FindEntry_no_match          54314487 ns   54272272 ns         13
FindEntry_no_match          53866923 ns   53851178 ns         13
FindEntry_no_match          53324423 ns   53317296 ns         13
FindEntry_no_match          53289231 ns   53289159 ns         13
FindEntry_no_match_mean     53619564 ns   53604216 ns         13
FindEntry_no_match_stddev     458449 ns     443527 ns          0
Iterate_all_files          128211111 ns  112254783 ns          6
Iterate_all_files          110695000 ns  110677726 ns          6
Iterate_all_files          109351250 ns  109350998 ns          6
Iterate_all_files          109367500 ns  109367796 ns          6
Iterate_all_files          110872222 ns  110591407 ns          6
Iterate_all_files_mean     113699417 ns  110448542 ns          6
Iterate_all_files_stddev     8143723 ns    1194577 ns          0

$ cd system/core/libziparchive
$ git checkout HEAD~
$ git am 0001-use-std-hash.patch
$ mma
$ cd -
$ adb push out/target/product/hikey/data/benchmarktest64/ziparchive-benchmarks /data
$ adb shell /data/ziparchive-benchmarks --benchmark_repetitions=5
-----------------------------------------------------------------
Benchmark                          Time           CPU Iterations
-----------------------------------------------------------------
FindEntry_no_match          55339872 ns   55195112 ns         13
FindEntry_no_match          56232628 ns   56069924 ns         13
FindEntry_no_match          55694103 ns   55255946 ns         13
FindEntry_no_match          55275064 ns   55120136 ns         13
FindEntry_no_match          54971987 ns   54944411 ns         13
FindEntry_no_match_mean     55502731 ns   55317106 ns         13
FindEntry_no_match_stddev     482032 ns     436766 ns          0
Iterate_all_files          114618611 ns  114487804 ns          6
Iterate_all_files          112552917 ns  112229801 ns          6
Iterate_all_files          111288750 ns  111255044 ns          6
Iterate_all_files          111291528 ns  111259045 ns          6
Iterate_all_files          114347222 ns  113677119 ns          6
Iterate_all_files_mean     112819806 ns  112581763 ns          6
Iterate_all_files_stddev     1606214 ns    1454858 ns          0

Change-Id: I1e3413d331bcb460ca38bc2c87e23f89b456cd2f
parent c021b75c
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