vasilito/RedBear-OS
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

base: Add e1000d interrupt throttling rate (ITR) coalescing (P53)

Browse Source 
Re-implements work that was lost due to ephemeral source/ subdirectory.
ITR dynamically adjusts interrupt coalescing based on packet rate.

- Add ITR register (0xC4) and set_itr() to device.rs
- Add itr.rs tracker with hysteresis-based rate adaptation
- Wire tracker into IRQ handler in main.rs
- Document in AGENTS.md: source/ is ALWAYS rewritten
This commit is contained in:
Admin Pupkin
2026-05-20 22:15:03 +03:00
parent ac2f1ccbc2
commit 0046c76e43
4 changed files with 126 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files
AGENTS.md
+5 -3
View File
@@ -21,9 +21,11 @@ All recipe sources are pinned and archived in `sources/redbear-0.1.0/`.
## BUILD SYSTEM DURABILITY — THE CARDINAL RULE
**Never edit files under `recipes/*/source/` directly. Those trees are ephemeral — they are
destroyed and regenerated on every `repo fetch`, `repo cook`, `make clean`, and
`make distclean`. Any edit made there will be silently lost on the next build.**
**THE `recipes/*/source/` DIRECTORY WILL ALWAYS BE REWRITTEN. DO NOT EVER USE IT FOR ANY
WORK THAT YOU INTEND TO KEEP. THOSE TREES ARE EPHEMERAL — THEY ARE DESTROYED AND REGENERATED
ON EVERY `repo fetch`, `repo cook`, `make clean`, AND `make distclean`. ANY EDIT MADE THERE
WILL BE SILENTLY LOST ON THE NEXT BUILD. COMMITTING TO A SUBMODULE INSIDE `source/` DOES NOT
PROTECT YOUR WORK — THE ENTIRE DIRECTORY IS DELETED AND RE-CLONED/RE-EXTRACTED FROM SCRATCH.**
This is the #1 mistake AI agents and new contributors make. It has caused repeated work loss
in this project. The rule is:
local/patches/base/P53-e1000d-itr-coalescing.patch
+118
View File
@@ -0,0 +1,118 @@
diff --git a/drivers/net/e1000d/src/device.rs b/drivers/net/e1000d/src/device.rs
index 4c518f30..7ba100dd 100644
--- a/drivers/net/e1000d/src/device.rs
+++ b/drivers/net/e1000d/src/device.rs
@@ -26,0 +27 @@ const ICR: u32 = 0xC0;
+const ITR: u32 = 0xC4;
@@ -241,0 +243,6 @@ impl Intel8254x {
+ /// Set the Interrupt Throttling Rate (ITR) register.
+ /// `interval` is in 256-ns increments. 0 disables throttling.
+ pub unsafe fn set_itr(&self, interval: u16) {
+ self.write_reg(ITR, interval as u32);
+ }
+
diff --git a/drivers/net/e1000d/src/itr.rs b/drivers/net/e1000d/src/itr.rs
new file mode 100644
index 00000000..aa85a6f2
--- /dev/null
+++ b/drivers/net/e1000d/src/itr.rs
@@ -0,0 +1,81 @@
+/// Interrupt Throttling Rate (ITR) tracker for e1000d.
+///
+/// Dynamically adjusts the interrupt coalescing interval based on packet rate
+/// to balance latency and CPU overhead.
+#[derive(Debug)]
+pub struct ItrTracker {
+ last_irq_count: u64,
+ current_itr: u16,
+ consecutive_low: u32,
+ consecutive_high: u32,
+}
+
+impl ItrTracker {
+ /// Target ~8000 interrupts/sec max for low latency.
+ const LOW_LATENCY_THRESHOLD: u64 = 8000;
+ /// Target ~2000 interrupts/sec min for CPU efficiency.
+ const HIGH_THROUGHPUT_THRESHOLD: u64 = 2000;
+ /// Minimum ITR interval in 256-ns units (~50 µs).
+ const MIN_ITR: u16 = 200;
+ /// Default ITR interval in 256-ns units (~256 µs).
+ const DEFAULT_ITR: u16 = 1000;
+ /// Maximum ITR interval in 256-ns units (~2 ms).
+ const MAX_ITR: u16 = 8000;
+ /// Number of consecutive measurements before adjusting.
+ const HYSTERESIS: u32 = 3;
+
+ pub fn new() -> Self {
+ Self {
+ last_irq_count: 0,
+ current_itr: Self::DEFAULT_ITR,
+ consecutive_low: 0,
+ consecutive_high: 0,
+ }
+ }
+
+ /// Call once per IRQ to update the tracker and return the new ITR value.
+ /// Returns `None` if no change is needed.
+ pub fn update(&mut self, irq_count: u64) -> Option<u16> {
+ let delta = irq_count.saturating_sub(self.last_irq_count);
+ self.last_irq_count = irq_count;
+
+ if delta > Self::LOW_LATENCY_THRESHOLD {
+ self.consecutive_high += 1;
+ self.consecutive_low = 0;
+ if self.consecutive_high >= Self::HYSTERESIS {
+ self.consecutive_high = 0;
+ let new_itr = self.current_itr.saturating_mul(2).min(Self::MAX_ITR);
+ if new_itr != self.current_itr {
+ self.current_itr = new_itr;
+ return Some(self.current_itr);
+ }
+ }
+ } else if delta < Self::HIGH_THROUGHPUT_THRESHOLD {
+ self.consecutive_low += 1;
+ self.consecutive_high = 0;
+ if self.consecutive_low >= Self::HYSTERESIS {
+ self.consecutive_low = 0;
+ let new_itr = self.current_itr.saturating_div(2).max(Self::MIN_ITR);
+ if new_itr != self.current_itr {
+ self.current_itr = new_itr;
+ return Some(self.current_itr);
+ }
+ }
+ } else {
+ self.consecutive_low = 0;
+ self.consecutive_high = 0;
+ }
+
+ None
+ }
+
+ pub fn current_itr(&self) -> u16 {
+ self.current_itr
+ }
+}
+
+impl Default for ItrTracker {
+ fn default() -> Self {
+ Self::new()
+ }
+}
diff --git a/drivers/net/e1000d/src/main.rs b/drivers/net/e1000d/src/main.rs
index 373ea9b3..1a4b0667 100644
--- a/drivers/net/e1000d/src/main.rs
+++ b/drivers/net/e1000d/src/main.rs
@@ -8,0 +9 @@ pub mod device;
+pub mod itr;
@@ -46,0 +48,2 @@ fn daemon(daemon: daemon::Daemon, mut pcid_handle: PciFunctionHandle) -> ! {
+ let mut itr_tracker = itr::ItrTracker::new();
+
@@ -74,0 +78 @@ fn daemon(daemon: daemon::Daemon, mut pcid_handle: PciFunctionHandle) -> ! {
+ let mut irq_count: u64 = 0;
@@ -77,0 +82 @@ fn daemon(daemon: daemon::Daemon, mut pcid_handle: PciFunctionHandle) -> ! {
+ irq_count += 1;
@@ -82,0 +88,4 @@ fn daemon(daemon: daemon::Daemon, mut pcid_handle: PciFunctionHandle) -> ! {
+ if let Some(new_itr) = itr_tracker.update(irq_count) {
+ unsafe { scheme.adapter().set_itr(new_itr) };
+ }
+
recipes/core/base/P53-e1000d-itr-coalescing.patch
Symlink
+1
View File
@@ -0,0 +1 @@
../../../local/patches/base/P53-e1000d-itr-coalescing.patch
recipes/core/base/recipe.toml
+2
View File
@@ -105,6 +105,8 @@ patches = [
"P51-logd-rotation.patch",
# P52: Add ACPI C-state discovery and thermal-based C-state policy
"P52-acpid-cstates.patch",
# P53: Add e1000d interrupt throttling rate (ITR) coalescing
"P53-e1000d-itr-coalescing.patch",
]
[package]