Merge pull request #2251 from JuliDi/faq-performance-tweaks

[FAQ] Add section about speed optimization

1 files changed, 17 insertions, 0 deletions

diff --git a/docs/modules/ROOT/pages/faq.adoc b/docs/modules/ROOT/pages/faq.adoc
index df3f66658..cab9fb9d8 100644
--- a/docs/modules/ROOT/pages/faq.adoc
+++ b/docs/modules/ROOT/pages/faq.adoc
@@ -135,3 +135,20 @@ embassy-time = { git = "https://github.com/embassy-rs/embassy.git", rev = "e5fdd
 ----
 
 Note that the git revision should match any other embassy patches or git dependencies that you are using!
+
+== How can I optimize the speed of my embassy-stm32 program?
+
+* Make sure RCC is set up to go as fast as possible
+* Make sure link:https://docs.rs/cortex-m/latest/cortex_m/peripheral/struct.SCB.html[flash cache] is enabled
+* build with `--release`
+* Set the following keys for the release profile in your `Cargo.toml`:
+    ** `opt-level = "s"`
+    ** `lto = "fat"`
+* Set the following keys in the `[unstable]` section of your `.cargo/config.toml`
+    ** `build-std = ["core"]`
+    ** `build-std-features = ["panic_immediate_abort"]`
+* Enable feature `embassy-time/generic-queue`, disable feature `embassy-executor/integrated-timers`
+* When using `InterruptExecutor`:
+    ** disable `executor-thread`
+    ** make `main`` spawn everything, then enable link:https://docs.rs/cortex-m/latest/cortex_m/peripheral/struct.SCB.html#method.set_sleeponexit[SCB.SLEEPONEXIT] and `loop { cortex_m::asm::wfi() }`
+    ** *Note:*  If you need 2 priority levels, using 2 interrupt executors is better than 1 thread executor + 1 interrupt executor.
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