# Binary Size Profiling
The bloaty_compare_master
build target allows you to get a better understanding of the impact of changes on code size. When it is used, the toolchain downloads the latest successful master build of a particular firmware and compares it to the local build (using the bloaty (opens new window) size profiler for binaries).
提示
This can help analyse changes that (may) cause px4_fmu-v2_default
to hit the 1MB flash limit.
Bloaty must be in your path and found at cmake configure time. The PX4 docker files (opens new window) install bloaty as shown:
git clone --recursive https://github.com/google/bloaty.git /tmp/bloaty \
&& cd /tmp/bloaty && cmake -GNinja . && ninja bloaty && cp bloaty /usr/local/bin/ \
&& rm -rf /tmp/*
The example below shows how you might see the impact of removing the mpu9250 driver from px4_fmu-v2_default
. First it locally sets up a build without the driver:
% git diff
diff --git a/boards/px4/fmu-v2/default.px4board b/boards/px4/fmu-v2/default.px4board
index 40d7778..2ce7972 100644
--- a/boards/px4/fmu-v2/default.px4board
+++ b/boards/px4/fmu-v2/default.px4board
@@ -36,7 +36,7 @@
- CONFIG_DRIVERS_IMU_INVENSENSE_MPU9250=y
+ CONFIG_DRIVERS_IMU_INVENSENSE_MPU9250=n
Then use the make target, specifying the target build to compare (px4_fmu-v2_default
in this case):
% make px4_fmu-v2_default bloaty_compare_master
...
...
...
VM SIZE FILE SIZE
-------------- --------------
[DEL] -52 MPU9250::check_null_data(unsigned int*, unsigned char) -52 [DEL]
[DEL] -52 MPU9250::test_error() -52 [DEL]
[DEL] -52 MPU9250_gyro::MPU9250_gyro(MPU9250*, char const*) -52 [DEL]
[DEL] -56 mpu9250::info(MPU9250_BUS) -56 [DEL]
[DEL] -56 mpu9250::regdump(MPU9250_BUS) -56 [DEL]
... -336 [DEL]
[DEL] -344 MPU9250_mag::_measure(ak8963_regs) -344 [DEL]
[DEL] -684 MPU9250::MPU9250(device::Device*, device::Device*, char const*, char const*, cha -684 [DEL]
[DEL] -684 MPU9250::init() -684 [DEL]
[DEL] -1000 MPU9250::measure() -1000 [DEL]
-41.3% -1011 [43 Others] -1011 -41.3%
-1.0% -1.05Ki [Unmapped] +24.2Ki +0.2%
-1.0% -10.3Ki TOTAL +14.9Ki +0.1%
This shows that removing mpu9250 from px4_fmu-v2_default
would save 10.3 kB of flash. It also shows the sizes of different pieces of the mpu9250 driver.