On 06/01/17 22:19 +0000, Aditya K wrote:
Could you try the corrected patch on your benchmarks?
For the test-case you gave there is a regression.
Benchmark
Time CPU Iterations
-------------------------------------------------------------------
Without the patch: BM_StringRegression 81 ns 81 ns
8503740
With the patch: BM_StringRegression 109 ns 109 ns
6346500
The real advantage is when there are fewer matches as seen in
BM_StringFindNoMatch. The code for the benchmark can be found in
https://github.com/llvm-mirror/libcxx/blob/master/benchmarks/string.bench.cpp
However, I have written an independent std-benchmark that can be used just by
exporting the CC, CXX, LD_LIBRARY_FLAGS:
https://github.com/hiraditya/std-benchmark
I think the large improvements are worth the smaller regression, so
I'm committing the patch I sent last week.
Following are the results:
----------------------------------------------------------------------------------------------------------------------------------
Without the patch:
Run on (8 X 3403.85 MHz CPU s)
2017-01-06 15:47:30
***WARNING*** CPU scaling is enabled, the benchmark real time measurements may
be noisy and will incur extra overhead.
Benchmark Time CPU Iterations
-------------------------------------------------------------------
BM_StringFindNoMatch/10 6 ns 6 ns 114499418
BM_StringFindNoMatch/64 34 ns 34 ns 20578576
BM_StringFindNoMatch/512 222 ns 222 ns 3136787
BM_StringFindNoMatch/4096 1728 ns 1729 ns 401913
BM_StringFindNoMatch/32768 13679 ns 13684 ns 50680
BM_StringFindNoMatch/131072 54570 ns 54591 ns 12506
BM_StringFindAllMatch/1 4 ns 4 ns 180640260
BM_StringFindAllMatch/8 6 ns 6 ns 119682220
BM_StringFindAllMatch/64 7 ns 7 ns 97679753
BM_StringFindAllMatch/512 19 ns 19 ns 36035174
BM_StringFindAllMatch/4096 92 ns 92 ns 7516363
BM_StringFindAllMatch/32768 849 ns 849 ns 809284
BM_StringFindAllMatch/131072 3610 ns 3611 ns 193894
BM_StringFindMatch1/1 27273 ns 27283 ns 25579
BM_StringFindMatch1/8 27289 ns 27300 ns 25516
BM_StringFindMatch1/64 27297 ns 27307 ns 25561
BM_StringFindMatch1/512 27303 ns 27314 ns 25579
BM_StringFindMatch1/4096 27488 ns 27499 ns 25366
BM_StringFindMatch1/32768 28157 ns 28168 ns 24750
BM_StringFindMatch2/1 27273 ns 27284 ns 25562
BM_StringFindMatch2/8 27296 ns 27306 ns 25555
BM_StringFindMatch2/64 27312 ns 27323 ns 25549
BM_StringFindMatch2/512 27327 ns 27338 ns 25558
BM_StringFindMatch2/4096 27513 ns 27524 ns 25349
BM_StringFindMatch2/32768 28161 ns 28172 ns 24788
BM_StringRegression 81 ns 81 ns 8503740
With the patch
Run on (8 X 1071.8 MHz CPU s)
2017-01-06 16:06:29
***WARNING*** CPU scaling is enabled, the benchmark real time measurements may
be noisy and will incur extra overhead.
Benchmark Time CPU Iterations
-------------------------------------------------------------------
BM_StringFindNoMatch/10 6 ns 6 ns 121302159
BM_StringFindNoMatch/64 7 ns 7 ns 102003502
BM_StringFindNoMatch/512 15 ns 15 ns 44820639
BM_StringFindNoMatch/4096 77 ns 77 ns 9016958
BM_StringFindNoMatch/32768 555 ns 555 ns 1227219
BM_StringFindNoMatch/131072 2688 ns 2689 ns 259488
BM_StringFindAllMatch/1 8 ns 8 ns 85893410
BM_StringFindAllMatch/8 9 ns 9 ns 80811804
BM_StringFindAllMatch/64 9 ns 9 ns 74237599
BM_StringFindAllMatch/512 23 ns 23 ns 31163379
BM_StringFindAllMatch/4096 94 ns 94 ns 7317385
BM_StringFindAllMatch/32768 847 ns 848 ns 803901
BM_StringFindAllMatch/131072 3551 ns 3552 ns 196844
BM_StringFindMatch1/1 1337 ns 1337 ns 518042
BM_StringFindMatch1/8 1338 ns 1338 ns 519431
BM_StringFindMatch1/64 1340 ns 1341 ns 513974
BM_StringFindMatch1/512 1355 ns 1356 ns 511857
BM_StringFindMatch1/4096 1489 ns 1489 ns 465629
BM_StringFindMatch1/32768 2203 ns 2204 ns 316044
BM_StringFindMatch2/1 1337 ns 1338 ns 519057
BM_StringFindMatch2/8 1337 ns 1337 ns 517745
BM_StringFindMatch2/64 1347 ns 1347 ns 514813
BM_StringFindMatch2/512 1362 ns 1363 ns 507408
BM_StringFindMatch2/4096 1491 ns 1492 ns 465979
BM_StringFindMatch2/32768 2204 ns 2205 ns 315887
BM_StringRegression 109 ns 109 ns 6346500
-Aditya
From: Jonathan Wakely <jwak...@redhat.com>
Sent: Friday, January 6, 2017 2:37 PM
To: Aditya Kumar
Cc: libstd...@gcc.gnu.org; gcc-patches@gcc.gnu.org; hiradi...@msn.com
Subject: Re: [PATCH] improve string find algorithm
On 06/01/17 14:34 -0600, Aditya Kumar wrote:
Thanks for the correction and updating the comments.
Could you try the corrected patch on your benchmarks?
The performance with the patch is worse for the first string::find
benchmark in our testsuite:
s = "aabbaabbaaxd adbffdadgaxaabbbddhatyaaaabbbaabbaabbcsy";
f = "aabbaabbc";
s.find(f);
