Using SystemTap userspace static probes

One of the new features in glibc 2.19 was a set of SystemTap static probes in the malloc subsystem to allow a better view into its inner workings. SystemTap static probe points expand to only a single nop instruction when not enabled and take a fixed number of arguments which are passed to your SystemTap probe as arguments. I wanted to use these probes to analyze the performance of a malloc workload, so I wrote a SystemTap script to log events in the malloc subsystem.

To get this script to work on Fedora 20 I had to install the git version of SystemTap or some of the probes failed to parse
their arguments correctly. The script can be run like this:


# stap malloc.stp -c /usr/bin/ls

It’s also possible to run this script using non-installed version of glibc if you modify the globs in the script to match the path to your libc and run it with the appropriate library path:


# stap malloc.stp -c "env 'LD_LIBRARY_PATH=.../glibc-build:.../glibc-build/nptl' /usr/bin/ls"

The script is very simple and just prints a timestamp, the name of the probe point and the arguments but I hope someone will find it useful.


probe process("/lib*/libc.so.*").mark("memory_heap_new") {
printf("%d:memory_heap_new heap %x size %dn",
gettimeofday_ms(), $arg1, $arg2)
}

probe process("/lib*/libc.so.*").mark("memory_heap_more") {
printf("%d:memory_heap_more heap %x size %dn",
gettimeofday_ms(), $arg1, $arg2)
}

probe process("/lib*/libc.so.*").mark("memory_heap_less") {
printf("%d:memory_heap_less heap %x size %dn",
gettimeofday_ms(), $arg1, $arg2)
}

probe process("/lib*/libc.so.*").mark("memory_heap_free") {
printf("%d:memory_heap_free heap %x size %dn",
gettimeofday_ms(), $arg1, $arg2)
}

probe process("/lib*/libc.so.*").mark("memory_arena_new") {
printf("%d:memory_arena_new arena %x size %dn",
gettimeofday_ms(), $arg1, $arg2)
}

probe process("/lib*/libc.so.*").mark("memory_arena_reuse_free_list") {
printf("%d:memory_arena_reuse_free_list free_list %xn",
gettimeofday_ms(), $arg1)
}

probe process("/lib*/libc.so.*").mark("memory_arena_reuse_wait") {
printf("%d:memory_arena_reuse_wait mutex %d arena %x avoid_arena %xn",
gettimeofday_ms(), $arg1, $arg2, $arg3)
}

probe process("/lib*/libc.so.*").mark("memory_arena_reuse") {
printf("%d:memory_arena_reuse arena %x avoid_arena %xn",
gettimeofday_ms(), $arg1, $arg2)
}

probe process("/lib*/libc.so.*").mark("memory_arena_retry") {
printf("%d:memory_arena_retry arena %x bytes %dn",
gettimeofday_ms(), $arg2, $arg1)
}

probe process("/lib*/libc.so.*").mark("memory_sbrk_more") {
printf("%d:memory_sbrk_more brk %x change %dn",
gettimeofday_ms(), $arg1, $arg2)
}

probe process("/lib*/libc.so.*").mark("memory_sbrk_less") {
printf("%d:memory_sbrk_less brk %x change %dn",
gettimeofday_ms(), $arg1, $arg2)
}

probe process("/lib*/libc.so.*").mark("memory_malloc_retry") {
printf("%d:memory_malloc_retry bytes %dn",
gettimeofday_ms(), $arg1)
}

probe process("/lib*/libc.so.*").mark("memory_mallopt_free_dyn_thresholds") {
printf("%d:memory_mallopt_free_dyn_thresholds mmap %d trim %dn",
gettimeofday_ms(), $arg1, $arg2)
}

probe process("/lib*/libc.so.*").mark("memory_realloc_retry") {
printf("%d:memory_realloc_retry bytes %d oldmem %xn",
gettimeofday_ms(), $arg1, $arg2)
}

probe process("/lib*/libc.so.*").mark("memory_memalign_retry") {
printf("%d:memory_memalign_retry bytes %d alignment %dn",
gettimeofday_ms(), $arg1, $arg2)
}

probe process("/lib*/libc.so.*").mark("memory_calloc_retry") {
printf("%d:memory_calloc_retry bytes %dn",
gettimeofday_ms(), $arg1)
}

probe process("/lib*/libc.so.*").mark("memory_mallopt") {
printf("%d:memory_mallopt param %d value %dn",
gettimeofday_ms(), $arg1, $arg2)
}

probe process("/lib*/libc.so.*").mark("memory_mallopt_mxfast") {
printf("%d:memory_mallopt_mxfast new %d old %dn",
gettimeofday_ms(), $arg1, $arg2)
}

probe process("/lib*/libc.so.*").mark("memory_mallopt_trim_threshold") {
printf("%d:memory_mallopt_trim_threshold new %d old %d dyn_threshold %dn",
gettimeofday_ms(), $arg1, $arg2, $arg3)
}

probe process("/lib*/libc.so.*").mark("memory_mallopt_top_pad") {
printf("%d:memory_mallopt_top_pad new %d old %d dyn_threshold %dn",
gettimeofday_ms(), $arg1, $arg2, $arg3)
}

probe process("/lib*/libc.so.*").mark("memory_mallopt_mmap_threshold") {
printf("%d:memory_mallopt_mmap_threshold new %d old %d dyn_threshold %dn",
gettimeofday_ms(), $arg1, $arg2, $arg3)
}

probe process("/lib*/libc.so.*").mark("memory_mallopt_mmap_max") {
printf("%d:memory_mallopt_mmap_max new %d old %d dyn_threshold %dn",
gettimeofday_ms(), $arg1, $arg2, $arg3)
}

probe process("/lib*/libc.so.*").mark("memory_mallopt_check_action") {
printf("%d:memory_mallopt_check_action new %d old %dn",
gettimeofday_ms(), $arg1, $arg2)
}

probe process("/lib*/libc.so.*").mark("memory_mallopt_perturb") {
printf("%d:memory_mallopt_perturb new %d old %dn",
gettimeofday_ms(), $arg1, $arg2)
}

probe process("/lib*/libc.so.*").mark("memory_mallopt_arena_test") {
printf("%d:memory_mallopt_arena_test new %d old %dn",
gettimeofday_ms(), $arg1, $arg2)
}

probe process("/lib*/libc.so.*").mark("memory_mallopt_arena_max") {
printf("%d:memory_mallopt_arena_max new %d old %dn",
gettimeofday_ms(), $arg1, $arg2)
}

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