binder: Replace use of resize()/memcpy() with reserve()/insert()
resize() zero initializes the vector even though data is about to be
copied to it. Moreover it does so with a loop rather than a memset.
Using reserve() and insert() is significantly faster with large
payloads, as it only has to allocate and memcpy.
Benchmarked using system/libhwbinder/tests/benchmarks
Before:
Benchmark Time CPU Iterations
-------------------------------------------------------------
BM_sendVec_binder/4k 89872 ns 45885 ns 15328
BM_sendVec_binder/8k 122753 ns 57713 ns 11667
BM_sendVec_binder/16k 163825 ns 88444 ns 7500
BM_sendVec_binder/32k 261942 ns 153561 ns 4667
BM_sendVec_binder/64k 558372 ns 318525 ns 2386
After:
Benchmark Time CPU Iterations
-------------------------------------------------------------
BM_sendVec_binder/4k 69052 ns 23111 ns 30000
BM_sendVec_binder/8k 71891 ns 25092 ns 27632
BM_sendVec_binder/16k 85439 ns 32822 ns 21429
BM_sendVec_binder/32k 115223 ns 43912 ns 15789
BM_sendVec_binder/64k 203960 ns 82667 ns 8750
Change-Id: Ie83c1d0a9da6f175ffd1a3fc9e0ecc6d542a909a
1 file changed