docs/devel: document the test plugins

Although the test plugins are fairly basic they are still useful for
some things so we should document their existence.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20220929114231.583801-41-alex.bennee@linaro.org>
This commit is contained in:
Alex Bennée 2022-09-29 12:42:20 +01:00
parent 8c1f1020d6
commit 59195c6558

View file

@ -145,12 +145,141 @@ Example Plugins
There are a number of plugins included with QEMU and you are
encouraged to contribute your own plugins plugins upstream. There is a
``contrib/plugins`` directory where they can go.
``contrib/plugins`` directory where they can go. There are also some
basic plugins that are used to test and exercise the API during the
``make check-tcg`` target in ``tests\plugins``.
- tests/plugins
- tests/plugins/empty.c
These are some basic plugins that are used to test and exercise the
API during the ``make check-tcg`` target.
Purely a test plugin for measuring the overhead of the plugins system
itself. Does no instrumentation.
- tests/plugins/bb.c
A very basic plugin which will measure execution in course terms as
each basic block is executed. By default the results are shown once
execution finishes::
$ qemu-aarch64 -plugin tests/plugin/libbb.so \
-d plugin ./tests/tcg/aarch64-linux-user/sha1
SHA1=15dd99a1991e0b3826fede3deffc1feba42278e6
bb's: 2277338, insns: 158483046
Behaviour can be tweaked with the following arguments:
* inline=true|false
Use faster inline addition of a single counter. Not per-cpu and not
thread safe.
* idle=true|false
Dump the current execution stats whenever the guest vCPU idles
- tests/plugins/insn.c
This is a basic instruction level instrumentation which can count the
number of instructions executed on each core/thread::
$ qemu-aarch64 -plugin tests/plugin/libinsn.so \
-d plugin ./tests/tcg/aarch64-linux-user/threadcount
Created 10 threads
Done
cpu 0 insns: 46765
cpu 1 insns: 3694
cpu 2 insns: 3694
cpu 3 insns: 2994
cpu 4 insns: 1497
cpu 5 insns: 1497
cpu 6 insns: 1497
cpu 7 insns: 1497
total insns: 63135
Behaviour can be tweaked with the following arguments:
* inline=true|false
Use faster inline addition of a single counter. Not per-cpu and not
thread safe.
* sizes=true|false
Give a summary of the instruction sizes for the execution
* match=<string>
Only instrument instructions matching the string prefix. Will show
some basic stats including how many instructions have executed since
the last execution. For example::
$ qemu-aarch64 -plugin tests/plugin/libinsn.so,match=bl \
-d plugin ./tests/tcg/aarch64-linux-user/sha512-vector
...
0x40069c, 'bl #0x4002b0', 10 hits, 1093 match hits, Δ+1257 since last match, 98 avg insns/match
0x4006ac, 'bl #0x403690', 10 hits, 1094 match hits, Δ+47 since last match, 98 avg insns/match
0x4037fc, 'bl #0x4002b0', 18 hits, 1095 match hits, Δ+22 since last match, 98 avg insns/match
0x400720, 'bl #0x403690', 10 hits, 1096 match hits, Δ+58 since last match, 98 avg insns/match
0x4037fc, 'bl #0x4002b0', 19 hits, 1097 match hits, Δ+22 since last match, 98 avg insns/match
0x400730, 'bl #0x403690', 10 hits, 1098 match hits, Δ+33 since last match, 98 avg insns/match
0x4037ac, 'bl #0x4002b0', 12 hits, 1099 match hits, Δ+20 since last match, 98 avg insns/match
...
For more detailed execution tracing see the ``execlog`` plugin for
other options.
- tests/plugins/mem.c
Basic instruction level memory instrumentation::
$ qemu-aarch64 -plugin tests/plugin/libmem.so,inline=true \
-d plugin ./tests/tcg/aarch64-linux-user/sha1
SHA1=15dd99a1991e0b3826fede3deffc1feba42278e6
inline mem accesses: 79525013
Behaviour can be tweaked with the following arguments:
* inline=true|false
Use faster inline addition of a single counter. Not per-cpu and not
thread safe.
* callback=true|false
Use callbacks on each memory instrumentation.
* hwaddr=true|false
Count IO accesses (only for system emulation)
- tests/plugins/syscall.c
A basic syscall tracing plugin. This only works for user-mode. By
default it will give a summary of syscall stats at the end of the
run::
$ qemu-aarch64 -plugin tests/plugin/libsyscall \
-d plugin ./tests/tcg/aarch64-linux-user/threadcount
Created 10 threads
Done
syscall no. calls errors
226 12 0
99 11 11
115 11 0
222 11 0
93 10 0
220 10 0
233 10 0
215 8 0
214 4 0
134 2 0
64 2 0
96 1 0
94 1 0
80 1 0
261 1 0
78 1 0
160 1 0
135 1 0
- contrib/plugins/hotblocks.c