F´ (FPrime) memory footprint benchmark

This project aims to make a brief benchmark of the memory footprint of the F' framework to get an idea of it.

In order to evaluate the memory footprint of F´ we simplified the reference deployment topology "Ref", which we replicated in "App" and then simplified. The metrics considered relevant to evaluate the minimum size of F´ are:

• the size of the .text/.rodata/.data/.bss sections of the binary
• the size of the ELF
• the size of the binary from the ELF by the command objcopy -O binary App App.bin.

ELF Header
Class	ELF64
Data	2's complement, little endian
OS/ABI	UNIX - System V
ABI Version	0
Machine	Advanced Micro Devices X86-64

Customing F´ symbols only

Initially we measured these artifacts only by customizing some symbols dimensioning the compiled code of the framework. Let's say:

• FW_OBJECT_NAMES,
• FW_OBJECT_REGISTRATION,
• FW_PORT_TRACING,
• FW_ENABLE_TEXT_LOGGING,
• FW_SERIALIZABLE_TO_STRING,
• FW_PORT_SERIALIZATION.

So notice that we didn't play with the options passed to the compiler or the linker at all. In fact, no options are passed to both, except for warnings to the compiler.

For more information, see the note on the configuration of F´ available in the project documentation: fprime/docs/UsersGuide/dev/configuring-fprime.md

All measurements were made with GNU 10.3.0 at commit 7890e7d of the project, which is the 4900th commit 😁.

We proceeded in 7 steps, the step n repeats the same configurations as the previous step n-1 to which we add a delta by deactivating a previously activated symbol.

Step	Description	Size .text	Size .rodata	Size .data	Size .bss	Size elf	Size bin
1	Default	26 Kb	3.2 Kb	24 bits	760 bits	77'576 bits	56'576 bits
2	FW_OBJECT_NAMES = 0	24.5 Kb	2.7 Kb	24 bits	296 bits	77'184 bits	56'576 bits
3	FW_OBJECT_REGISTRATION = 0	24.3 Kb	2.7 Kb	24 bits	288 bits	76'768 bits	56'576 bits
4	FW_PORT_TRACING = 0	23.7 Kb	2.7 Kb	24 bits	224 bits	71'976 bits	52'480 bits
5	FW_ENABLE_TEXT_LOGGING = 0	23.7 Kb	2.7 Kb	24 bits	224 bits	71'976 bits	52'480 bits
6	FW_SERIALIZABLE_TO_STRING = 0	21.5 Kb	2.4 Kb	24 bits	224 bits	66'192 bits	48'384 bits
7	FW_PORT_SERIALIZATION = 0	10.2 Kb	2.1 Kb	24 bits	216 bits	43'752 bits	32'000 bits

Customizing the toolchain options

Regarding the options passed to the toolchain, i.e. the compiler and the linker, we did not see any real difference compared to the measurements obtained in step 7. Only the linker option in step 5 subtly reduces the footprint - insignificant. We marked "x" when the value did not change.

Step	Description	Size .text	Size .rodata	Size .data	Size .bss	Size elf	Size bin
1	Step 7 configuration	10.197 Kb	2.178 Kb	24 bits	216 bits	43'752 bits	32'000 bits
2	-fno-exceptions -fno-rtti	x Kb	x Kb	x bits	x bits	x Kb	x Kb
3	-ffunction-sections -fdata-sections	x Kb	x Kb	x bits	x bits	x Kb	x Kb
4	-flto	x Kb	x Kb	x bits	x bits	x Kb	x Kb
5	-Wl,--gc-sections	10.133 Kb	2.154 Kb	16 bits	x bits	x Kb	31'992 bits
6	-fno-unroll-loops	x Kb	x Kb	x bits	x bits	x Kb	x Kb
7	-fno-jump-tables	x Kb	x Kb	x bits	x bits	x Kb	x Kb