[PATCH] mingw: use OpenSSL's SHA-1 routines

From: Jeff Hostetler <jeffhost@microsoft.com>

Use OpenSSL's SHA-1 routines rather than builtin block-sha1 routines. This improves performance on SHA1 operations on Intel processors.

OpenSSL 1.0.2 has made considerable performance improvements and support the Intel hardware acceleration features. See: https://software.intel.com/en-us/articles/improving-openssl-performance https://software.intel.com/en-us/articles/intel-sha-extensions

To test this I added/staged a single file in a gigantic repository having a 450MB index file. The code in read-cache.c verifies the header SHA as it reads the index and computes a new header SHA as it writes out the new index. Therefore, in this test the SHA code must process 900MB of data. Testing was done on an Intel I7-4770 CPU @ 3.40GHz (Intel64, Family 6, Model 60) CPU.

The block-sha1 version averaged 5.27 seconds. The OpenSSL version averaged 4.50 seconds.

================================================================

$ echo xxx >> project.mk $ time /e/blk_sha/bin/git.exe add project.mk

real 0m5.207s user 0m0.000s sys 0m0.250s

$ echo xxx >> project.mk $ time /e/blk_sha/bin/git.exe add project.mk

real 0m5.362s user 0m0.015s sys 0m0.234s

$ echo xxx >> project.mk $ time /e/blk_sha/bin/git.exe add project.mk

real 0m5.300s user 0m0.016s sys 0m0.250s

$ echo xxx >> project.mk $ time /e/blk_sha/bin/git.exe add project.mk

real 0m5.216s user 0m0.000s sys 0m0.250s

================================================================ $ echo xxx >> project.mk $ time /e/openssl/bin/git.exe add project.mk

real 0m4.431s user 0m0.000s sys 0m0.250s

$ echo xxx >> project.mk $ time /e/openssl/bin/git.exe add project.mk

real 0m4.478s user 0m0.000s sys 0m0.265s

$ echo xxx >> project.mk $ time /e/openssl/bin/git.exe add project.mk

real 0m4.690s user 0m0.000s sys 0m0.250s

$ echo xxx >> project.mk $ time /e/openssl/bin/git.exe add project.mk

real 0m4.420s user 0m0.000s sys 0m0.234s

================================================================

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
Published-As: https://github.com/dscho/git/releases/tag/mingw-openssl-sha1-v1
Fetch-It-Via: git fetch https://github.com/dscho/git mingw-openssl-sha1-v1

 config.mak.uname | 1 -
 1 file changed, 1 deletion(-)