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* perf/vg_perf:
Similarly to tests/vg_regtest, perf/vg_perf now accepts the 3
optional arguments:
--outer-valgrind
--outer-tool
--outer-args
This allows easy analysis or comparison of performance between
different Valgrind versions (e.g. using callgrind, or cachegrind/cg_diff).
* See README_DEVELOPERS for more details.
* vg_regtest modified so as to use the 'in-place' build of inner, rather
than the installed version.
* added option --smc-check=all-non-file to vg_perf and vg_regtest
outer default arguments (needed when evaluating a Valgrind which does
translation chaining).
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@12496
=============================================================================
Notes about performance benchmarks
=============================================================================
For each benchmark, here is a brief description and notes about its
strengths and weaknesses.
-----------------------------------------------------------------------------
Artificial stress tests
-----------------------------------------------------------------------------
bigcode1, bigcode2:
- Description: Executes a lot of (nonsensical) code.
- Strengths: Demonstrates the cost of translation which is a large part
of runtime, particularly on larger programs.
- Weaknesses: Highly artificial.
heap:
- Description: Does a lot of heap allocation and deallocation, and has a lot
of heap blocks live while doing so.
- Strengths: Stress test for an important sub-system; bug #105039 showed
that inefficiencies in heap allocation can make a big
difference to programs that allocate a lot.
- Weaknesses: Highly artificial -- allocation pattern is not real, and only
a few different size allocations are used.
sarp:
- Description: Does a lot of stack allocation and deallocation.
- Strengths: Tests for a specific performance bug that existed in 3.1.0 and
all earlier versions.
- Weaknesses: Highly artificial.
-----------------------------------------------------------------------------
Real programs
-----------------------------------------------------------------------------
bz2:
- Description: Burrows-Wheeler compression and decompression.
- Strengths: A real, widely used program, very similar to the 256.bzip2
SPEC2000 benchmark. Not dominated by any code, the hottest
55 blocks account for only 90% of execution. Has lots of
short blocks and stresses the memory system hard.
- Weaknesses: None, really, it's a good benchmark.
fbench:
- Description: Does some ray-tracing.
- Strengths: Moderately realistic program.
- Weaknesses: Dominated by sin and cos, which are not widely used, and are
hardware-supported on x86 but not on other platforms such as
PPC.
ffbench:
- Description: Does a Fast Fourier Transform (FFT).
- Strengths: Tests common FP ops (mostly adding and multiplying array
elements), FFT is a very important operation.
- Weaknesses: Dominated by the inner loop, which is quite long and flatters
Valgrind due to the small dispatcher overhead.
tinycc:
- Description: A very small and fast C compiler. A munged version of
Fabrice Bellard's TinyCC compiling itself multiple times.
- Strengths: A real program, lots of code (top 100 blocks only account for
47% of execution), involves large irregular data structures
(presumably, since it's a compiler). Does lots of
malloc/free calls and so changes that make a big improvement
to perf/heap typically cause a small improvement.
- Weaknesses None, really, it's a good benchmark.