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- Update COPYING and VEX/LICENSE.GPL to version 3. - Update README, NEWS, docs/manual license and contributing text. - Update file headers to say either version 3 of the License, or (at your option) any later version. - Leave tests and perf file headers as is, unless the code is derived from Valgrind/VEX. - Leave valgrind.h, cachegrind.h, callgrind.h, drd.h, helgrind.h, memcheck.h and dhat.h Hybrid-BSD licensed.
=============================================================================
Notes about performance benchmarks
=============================================================================
For each benchmark, here is a brief description and notes about its
strengths and weaknesses.
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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.