[Buildroot] [git commit branch/next] core: introduce BR2_ENABLE_RUNTIME_DEBUG
Yann E. MORIN
yann.morin.1998 at free.fr
Tue Jun 1 20:39:23 UTC 2021
Some packages have optional runtime assertions, extra traces, or other
elements that can help in debugging problems. However, such runtime elements
can negatively influence performance.
In a test program performing 100K gRPC calls from a client to a local server
and receiving the returned response, we see following execution time:
- runtime debug enabled: 1065 seconds
- runtime debug disabled: 48 seconds
This is more than a factor 20 (!) difference. Analysis shows that the
problem mostly stems from libabseil-cpp (a dependency of gRPC) which enables
mutex deadlock analysis when the preprocessor flag 'NDEBUG' is not set,
which adds a 'backtrace()' call on every lock/unlock. Potentially worse,
when libunwind is enabled and linked with the test program, 'backtrace()' is
not provided by glibc but by libunwind itself.
For production systems, users expect good performance out-of-the-box. In the
example above, the difference is huge and unless explicitly tested and
analyzed, users may not realize that the performance could be much better.
Address this problem by introducing a new option BR2_ENABLE_RUNTIME_DEBUG,
which can be used by packages or package infrastructures to set the
Note that BR2_ENABLE_RUNTIME_DEBUG is orthogonal to BR2_ENABLE_DEBUG: the
former changes runtime behavior, while the latter is only expected to add
debug symbols to the build. Today, the cmake build system does introduce a
runtime impact when BR2_ENABLE_DEBUG is set, but that will be rectified in a
Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire at nokia.com>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout at mind.be>
Reviewed-by: Yann E. MORIN <yann.morin.1998 at free.fr>
Signed-off-by: Yann E. MORIN <yann.morin.1998 at free.fr>
Config.in | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/Config.in b/Config.in
index c65e34bd5e..a008425688 100644
@@ -412,6 +412,19 @@ config BR2_DEBUG_3
+ bool "build packages with runtime debugging info"
+ Some packages may have runtime assertions, extra traces, and
+ similar runtime elements that can help debugging. However,
+ these elements may negatively influence performance so should
+ normally not be enabled on production systems.
+ Enable this option to enable such runtime debugging.
+ Note: disabling this option is not a guarantee that all
+ packages effectively removed these runtime debugging elements.
bool "strip target binaries"
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