mirror of
https://github.com/LadybirdBrowser/ladybird.git
synced 2024-11-22 07:30:19 +00:00
59a4e87a7e
After discussing on Discord about how to speed up the build time, I received lots of helpful advice on measuring the build time, but none of it was easily accessible. I thought other people might find it useful, so I've written it down! :^) Thanks goes to @bgianfo and @nico.
116 lines
7.4 KiB
Markdown
116 lines
7.4 KiB
Markdown
# Build profiling instructions
|
|
|
|
There are three ways you can get information about compile times:
|
|
|
|
1. Just using `time ninja install` instead of `ninja install` to time it overall.
|
|
2. Reading ninja's log files to get a per-file compile time.
|
|
3. Enabling GCC or Clang flags to get a more detailed per-file breakdown of times for compiler passes within a file.
|
|
|
|
## Ninja log files
|
|
|
|
Ninja produces a handy log file that includes a per-cpp-file compilation time. This is useful for discovering which files take the most time, and so are good targets for speeding up the overall build time. A python3 script named `ninjatracing` converts the ninja log file into a JSON format that's readable by several profile viewers.
|
|
|
|
### Prerequisites
|
|
|
|
`ninjatracing` is available on [GitHub](https://github.com/nico/ninjatracing/blob/master/ninjatracing)
|
|
|
|
It requires `python3`, available at `python`. You can either create the symlink yourself, or just modify the ninjatracing file to say `python3` instead of `python`.
|
|
|
|
You also need to make sure `ninjatracing` is marked as executable, and available from your PATH (or somewhere convenient where you can manually call it from).
|
|
|
|
### Usage
|
|
|
|
First, we need to clean the build (and `ccache` if present) to make sure every file gets compiled and gives a meaningful time reading.
|
|
```console
|
|
ninja clean
|
|
|
|
ccache --clear
|
|
```
|
|
|
|
Then, execute ninja as normal:
|
|
```console
|
|
ninja
|
|
```
|
|
|
|
The log will be written to `.ninja_log` in the current directory by default. To convert it to the more useful JSON file, call `ninjatracing` from the directory you called ninja from:
|
|
|
|
```console
|
|
ninjatracing .ninja_log > trace.json
|
|
|
|
```
|
|
|
|
You can then drag-and-drop the file onto [Speedscope](https://www.speedscope.app/) or any other compatible flamegraph visualizer.
|
|
|
|
## GCC/Clang
|
|
|
|
Adding the `-ftime-report` flag to GCC will cause it to output a breakdown for each file it compiles, which looks like this:
|
|
|
|
<details>
|
|
<summary>GCC -ftime-report output</summary>
|
|
|
|
```console
|
|
Time variable usr sys wall GGC
|
|
phase setup : 0.00 ( 0%) 0.00 ( 0%) 0.01 ( 0%) 1326k ( 2%)
|
|
phase parsing : 0.57 ( 61%) 0.19 ( 83%) 1.63 ( 65%) 59M ( 74%)
|
|
phase lang. deferred : 0.10 ( 11%) 0.03 ( 13%) 0.30 ( 12%) 8761k ( 11%)
|
|
phase opt and generate : 0.23 ( 25%) 0.01 ( 4%) 0.48 ( 19%) 10M ( 13%)
|
|
phase last asm : 0.03 ( 3%) 0.00 ( 0%) 0.08 ( 3%) 539k ( 1%)
|
|
|name lookup : 0.11 ( 12%) 0.01 ( 4%) 0.25 ( 10%) 2004k ( 2%)
|
|
|overload resolution : 0.08 ( 9%) 0.00 ( 0%) 0.26 ( 10%) 7900k ( 10%)
|
|
dump files : 0.02 ( 2%) 0.00 ( 0%) 0.00 ( 0%) 0 ( 0%)
|
|
callgraph construction : 0.04 ( 4%) 0.00 ( 0%) 0.06 ( 2%) 2677k ( 3%)
|
|
callgraph optimization : 0.00 ( 0%) 0.00 ( 0%) 0.01 ( 0%) 4752 ( 0%)
|
|
callgraph functions expansion : 0.15 ( 16%) 0.00 ( 0%) 0.32 ( 13%) 6267k ( 8%)
|
|
callgraph ipa passes : 0.03 ( 3%) 0.01 ( 4%) 0.08 ( 3%) 1413k ( 2%)
|
|
ipa inheritance graph : 0.00 ( 0%) 0.00 ( 0%) 0.02 ( 1%) 3760 ( 0%)
|
|
ipa profile : 0.00 ( 0%) 0.00 ( 0%) 0.01 ( 0%) 0 ( 0%)
|
|
trivially dead code : 0.01 ( 1%) 0.00 ( 0%) 0.00 ( 0%) 224 ( 0%)
|
|
df reg dead/unused notes : 0.01 ( 1%) 0.00 ( 0%) 0.00 ( 0%) 104k ( 0%)
|
|
alias analysis : 0.01 ( 1%) 0.00 ( 0%) 0.00 ( 0%) 70k ( 0%)
|
|
preprocessing : 0.06 ( 6%) 0.03 ( 13%) 0.16 ( 6%) 1365k ( 2%)
|
|
parser (global) : 0.04 ( 4%) 0.04 ( 17%) 0.13 ( 5%) 6894k ( 8%)
|
|
parser struct body : 0.09 ( 10%) 0.03 ( 13%) 0.20 ( 8%) 9020k ( 11%)
|
|
parser function body : 0.00 ( 0%) 0.00 ( 0%) 0.01 ( 0%) 83k ( 0%)
|
|
parser inl. func. body : 0.03 ( 3%) 0.01 ( 4%) 0.05 ( 2%) 1567k ( 2%)
|
|
parser inl. meth. body : 0.11 ( 12%) 0.03 ( 13%) 0.30 ( 12%) 10M ( 13%)
|
|
template instantiation : 0.27 ( 29%) 0.08 ( 35%) 0.89 ( 36%) 25M ( 32%)
|
|
constant expression evaluation : 0.01 ( 1%) 0.00 ( 0%) 0.01 ( 0%) 356k ( 0%)
|
|
constraint satisfaction : 0.01 ( 1%) 0.00 ( 0%) 0.02 ( 1%) 130k ( 0%)
|
|
early inlining heuristics : 0.00 ( 0%) 0.00 ( 0%) 0.02 ( 1%) 21k ( 0%)
|
|
inline parameters : 0.01 ( 1%) 0.00 ( 0%) 0.03 ( 1%) 146k ( 0%)
|
|
integration : 0.00 ( 0%) 0.00 ( 0%) 0.01 ( 0%) 564k ( 1%)
|
|
tree CFG cleanup : 0.00 ( 0%) 0.00 ( 0%) 0.01 ( 0%) 5768 ( 0%)
|
|
tree SSA other : 0.00 ( 0%) 0.00 ( 0%) 0.01 ( 0%) 13k ( 0%)
|
|
tree operand scan : 0.01 ( 1%) 0.00 ( 0%) 0.00 ( 0%) 429k ( 1%)
|
|
tree CCP : 0.01 ( 1%) 0.00 ( 0%) 0.00 ( 0%) 18k ( 0%)
|
|
expand : 0.01 ( 1%) 0.00 ( 0%) 0.03 ( 1%) 1303k ( 2%)
|
|
varconst : 0.00 ( 0%) 0.00 ( 0%) 0.04 ( 2%) 6744 ( 0%)
|
|
forward prop : 0.01 ( 1%) 0.00 ( 0%) 0.02 ( 1%) 3520 ( 0%)
|
|
CSE : 0.01 ( 1%) 0.00 ( 0%) 0.00 ( 0%) 1144 ( 0%)
|
|
loop fini : 0.00 ( 0%) 0.00 ( 0%) 0.01 ( 0%) 0 ( 0%)
|
|
branch prediction : 0.00 ( 0%) 0.01 ( 4%) 0.00 ( 0%) 20k ( 0%)
|
|
combiner : 0.01 ( 1%) 0.00 ( 0%) 0.02 ( 1%) 138k ( 0%)
|
|
integrated RA : 0.01 ( 1%) 0.00 ( 0%) 0.01 ( 0%) 1112k ( 1%)
|
|
LRA reload inheritance : 0.00 ( 0%) 0.00 ( 0%) 0.02 ( 1%) 13k ( 0%)
|
|
LRA create live ranges : 0.00 ( 0%) 0.00 ( 0%) 0.01 ( 0%) 8568 ( 0%)
|
|
reload CSE regs : 0.01 ( 1%) 0.00 ( 0%) 0.02 ( 1%) 100k ( 0%)
|
|
final : 0.00 ( 0%) 0.00 ( 0%) 0.02 ( 1%) 323k ( 0%)
|
|
variable output : 0.01 ( 1%) 0.00 ( 0%) 0.00 ( 0%) 15k ( 0%)
|
|
symout : 0.09 ( 10%) 0.00 ( 0%) 0.20 ( 8%) 13M ( 17%)
|
|
variable tracking : 0.00 ( 0%) 0.00 ( 0%) 0.04 ( 2%) 471k ( 1%)
|
|
var-tracking dataflow : 0.02 ( 2%) 0.00 ( 0%) 0.03 ( 1%) 18k ( 0%)
|
|
var-tracking emit : 0.00 ( 0%) 0.00 ( 0%) 0.04 ( 2%) 117k ( 0%)
|
|
rest of compilation : 0.01 ( 1%) 0.00 ( 0%) 0.03 ( 1%) 1258k ( 2%)
|
|
TOTAL : 0.93 0.23 2.50 79M
|
|
[24/3139] Building CXX object Kernel/CMakeFiles/Kernel.dir/CommandLine.cpp.o
|
|
```
|
|
|
|
</details>
|
|
|
|
Depending on whether you understand the internals of the compiler, this may or may not be helpful to you! Generally, this is not recommended.
|
|
|
|
Clang also supports `-ftime-report`, but I have not tested the output for it.
|
|
|
|
To add the flag, edit the `CMakeLists.txt` in the serenity root directory, and add `add_compile_options(-ftime-report)` to the list of compile options that start around line 220.
|
|
|
|
Additionally, you can add `-ftime-report-details` too, which again I have not tested.
|