thodg/libgit2/deps/chromium-zlib

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  • Hash : 83265b3e
    Author : lhchavez
    Date : 2020-12-18T06:50:22

    zlib: Add support for building with Chromium's zlib implementation This change builds libgit2 using Chromium's zlib implementation by invoking cmake with `-DUSE_BUNDLED_ZLIB=ON -DUSE_CHROMIUM_ZLIB=ON`, which is ~10% faster than the bundled zlib for the core::zstream suite. This version of zlib has some optimizations: a) Decompression (Intel+ARM): inflate_fast, adler32, crc32, etc. b) Compression (Intel): fill_window, longest_match, hash function, etc. Due to the introduction of SIMD optimizations, and to get the maximum performance out of this fork of zlib, this requires an x86_64 processor with SSE4.2 and CLMUL (anything Westmere or later, ~2010). The Chromium zlib implementation also supports ARM with NEON, but it has not been enabled in this patch. Performance =========== TL;DR: Running just `./libgit2_clar -score::zstream` 100 times in a loop took 0:56.30 before and 0:50.67 after (~10% reduction!). The bundled and system zlib implementations on an Ubuntu Focal system perform relatively similar (the bundled one is marginally better due to the compiler being able to inline some functions), so only the bundled and Chromium zlibs were compared. For a more balanced comparison (to ensure that nothing regressed overall), `libgit2_clar` under `perf` was also run, and the zlib-related functions were compared. Bundled ------- ```shell cmake \ -DUSE_BUNDLED_ZLIB=ON \ -DUSE_CHROMIUM_ZLIB=OFF \ -DCMAKE_BUILD_TYPE="RelWithDebInfo" \ -DCMAKE_C_FLAGS="-fPIC -fno-omit-frame-pointer" \ -GNinja \ .. ninja perf record --call-graph=dwarf ./libgit2_clar perf report --children ``` ``` Samples: 87K of event 'cycles', Event count (approx.): 75923450603 Children Self Command Shared Objec Symbol + 4.14% 0.01% libgit2_clar libgit2_clar [.] git_zstream_get_output_chunk + 2.91% 0.00% libgit2_clar libgit2_clar [.] git_zstream_get_output + 0.69% 0.00% libgit2_clar libgit2_clar [.] git_zstream_get_output (inlined) 0.17% 0.00% libgit2_clar libgit2_clar [.] git_zstream_init 0.02% 0.00% libgit2_clar libgit2_clar [.] git_zstream_reset 0.00% 0.00% libgit2_clar libgit2_clar [.] git_zstream_eos 0.00% 0.00% libgit2_clar libgit2_clar [.] git_zstream_done 0.00% 0.00% libgit2_clar libgit2_clar [.] git_zstream_free (inlined) Samples: 87K of event 'cycles', Event count (approx.): 75923450603 Children Self Command Shared Objec Symbol + 3.12% 0.01% libgit2_clar libgit2_clar [.] deflate + 2.65% 1.48% libgit2_clar libgit2_clar [.] deflate_slow + 1.60% 0.55% libgit2_clar libgit2_clar [.] inflate + 0.53% 0.00% libgit2_clar libgit2_clar [.] write_deflate 0.49% 0.36% libgit2_clar libgit2_clar [.] inflate_fast 0.46% 0.02% libgit2_clar libgit2_clar [.] deflate_fast 0.19% 0.19% libgit2_clar libgit2_clar [.] inflate_table 0.16% 0.01% libgit2_clar libgit2_clar [.] inflateInit_ 0.15% 0.00% libgit2_clar libgit2_clar [.] inflateInit2_ (inlined) 0.10% 0.00% libgit2_clar libgit2_clar [.] deflateInit_ 0.10% 0.00% libgit2_clar libgit2_clar [.] deflateInit2_ 0.03% 0.00% libgit2_clar libgit2_clar [.] deflateReset (inlined) 0.02% 0.00% libgit2_clar libgit2_clar [.] deflateReset 0.02% 0.00% libgit2_clar libgit2_clar [.] inflateEnd 0.02% 0.00% libgit2_clar libgit2_clar [.] deflateEnd 0.01% 0.00% libgit2_clar libgit2_clar [.] deflateResetKeep 0.01% 0.01% libgit2_clar libgit2_clar [.] inflateReset2 0.01% 0.00% libgit2_clar libgit2_clar [.] deflateReset (inlined) 0.00% 0.00% libgit2_clar libgit2_clar [.] inflateStateCheck (inlined) 0.00% 0.00% libgit2_clar libgit2_clar [.] inflateReset (inlined) 0.00% 0.00% libgit2_clar libgit2_clar [.] inflateStateCheck (inlined) 0.00% 0.00% libgit2_clar libgit2_clar [.] deflateStateCheck (inlined) 0.00% 0.00% libgit2_clar libgit2_clar [.] inflateResetKeep (inlined) ``` Chromium -------- ```shell cmake \ -DUSE_BUNDLED_ZLIB=ON \ -DUSE_CHROMIUM_ZLIB=ON \ -DCMAKE_BUILD_TYPE="RelWithDebInfo" \ -DCMAKE_C_FLAGS="-fPIC -fno-omit-frame-pointer" \ -GNinja \ .. ninja perf record --call-graph=dwarf ./libgit2_clar perf report --children ``` ``` Samples: 97K of event 'cycles', Event count (approx.): 80862210917 Children Self Command Shared Objec Symbol + 3.31% 0.00% libgit2_clar libgit2_clar [.] git_zstream_get_output_chunk + 2.27% 0.01% libgit2_clar libgit2_clar [.] git_zstream_get_output + 0.55% 0.00% libgit2_clar libgit2_clar [.] git_zstream_get_output (inlined) 0.18% 0.00% libgit2_clar libgit2_clar [.] git_zstream_init 0.02% 0.00% libgit2_clar libgit2_clar [.] git_zstream_reset 0.00% 0.00% libgit2_clar libgit2_clar [.] git_zstream_free (inlined) 0.00% 0.00% libgit2_clar libgit2_clar [.] git_zstream_done 0.00% 0.00% libgit2_clar libgit2_clar [.] git_zstream_free Samples: 97K of event 'cycles', Event count (approx.): 80862210917 Children Self Command Shared Objec Symbol + 2.55% 0.01% libgit2_clar libgit2_clar [.] deflate + 2.25% 1.41% libgit2_clar libgit2_clar [.] deflate_slow + 1.10% 0.52% libgit2_clar libgit2_clar [.] inflate 0.36% 0.00% libgit2_clar libgit2_clar [.] write_deflate 0.30% 0.03% libgit2_clar libgit2_clar [.] deflate_fast 0.28% 0.15% libgit2_clar libgit2_clar [.] inflate_fast_chunk_ 0.19% 0.19% libgit2_clar libgit2_clar [.] inflate_table 0.17% 0.01% libgit2_clar libgit2_clar [.] inflateInit_ 0.16% 0.00% libgit2_clar libgit2_clar [.] inflateInit2_ (inlined) 0.15% 0.00% libgit2_clar libgit2_clar [.] deflateInit_ 0.15% 0.00% libgit2_clar libgit2_clar [.] deflateInit2_ 0.11% 0.01% libgit2_clar libgit2_clar [.] adler32_z 0.09% 0.09% libgit2_clar libgit2_clar [.] adler32_simd_ 0.05% 0.00% libgit2_clar libgit2_clar [.] deflateReset (inlined) 0.05% 0.00% libgit2_clar libgit2_clar [.] deflate_read_buf 0.03% 0.00% libgit2_clar libgit2_clar [.] inflateEnd 0.02% 0.00% libgit2_clar libgit2_clar [.] deflateReset 0.01% 0.00% libgit2_clar libgit2_clar [.] deflateEnd 0.01% 0.01% libgit2_clar libgit2_clar [.] inflateReset2 0.01% 0.00% libgit2_clar libgit2_clar [.] inflateReset (inlined) 0.00% 0.00% libgit2_clar libgit2_clar [.] adler32 0.00% 0.00% libgit2_clar libgit2_clar [.] inflateResetKeep (inlined) 0.00% 0.00% libgit2_clar libgit2_clar [.] deflateResetKeep 0.00% 0.00% libgit2_clar libgit2_clar [.] inflateStateCheck (inlined) 0.00% 0.00% libgit2_clar libgit2_clar [.] inflateStateCheck (inlined) 0.00% 0.00% libgit2_clar libgit2_clar [.] inflateStateCheck (inlined) 0.00% 0.00% libgit2_clar libgit2_clar [.] deflateStateCheck (inlined) ```

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