diff --git a/cumulus/parachains/integration-tests/emulated/tests/coretime/coretime-rococo/src/tests/coretime_interface.rs b/cumulus/parachains/integration-tests/emulated/tests/coretime/coretime-rococo/src/tests/coretime_interface.rs
index 584bce8f1df76e3298bacf731986b84c9b55ff64..9915b1753ef6d2af0e5d4c49fa7b166ee68c959b 100644
--- a/cumulus/parachains/integration-tests/emulated/tests/coretime/coretime-rococo/src/tests/coretime_interface.rs
+++ b/cumulus/parachains/integration-tests/emulated/tests/coretime/coretime-rococo/src/tests/coretime_interface.rs
@@ -46,7 +46,7 @@ fn transact_hardcoded_weights_are_sane() {
// Create and populate schedule with the worst case assignment on this core.
let mut schedule = Vec::new();
- for i in 0..27 {
+ for i in 0..80 {
schedule.push(ScheduleItem {
mask: CoreMask::void().set(i),
assignment: CoreAssignment::Task(2000 + i),
diff --git a/cumulus/parachains/integration-tests/emulated/tests/coretime/coretime-westend/src/tests/coretime_interface.rs b/cumulus/parachains/integration-tests/emulated/tests/coretime/coretime-westend/src/tests/coretime_interface.rs
index f61bc4285a0cf24a2184d301da64ea48670961f0..00530f80b958d25f3af36ea17a63059d239831e7 100644
--- a/cumulus/parachains/integration-tests/emulated/tests/coretime/coretime-westend/src/tests/coretime_interface.rs
+++ b/cumulus/parachains/integration-tests/emulated/tests/coretime/coretime-westend/src/tests/coretime_interface.rs
@@ -46,7 +46,7 @@ fn transact_hardcoded_weights_are_sane() {
// Create and populate schedule with the worst case assignment on this core.
let mut schedule = Vec::new();
- for i in 0..27 {
+ for i in 0..80 {
schedule.push(ScheduleItem {
mask: CoreMask::void().set(i),
assignment: CoreAssignment::Task(2000 + i),
diff --git a/cumulus/parachains/runtimes/coretime/coretime-rococo/src/coretime.rs b/cumulus/parachains/runtimes/coretime/coretime-rococo/src/coretime.rs
index 76ee06a87e8d82dea17914e4f03647da2a5f307a..3910a747e9bb2d6026ec32406a8ccb4b1a21b3af 100644
--- a/cumulus/parachains/runtimes/coretime/coretime-rococo/src/coretime.rs
+++ b/cumulus/parachains/runtimes/coretime/coretime-rococo/src/coretime.rs
@@ -218,6 +218,36 @@ impl CoretimeInterface for CoretimeAllocator {
end_hint: Option<RCBlockNumberOf<Self>>,
) {
use crate::coretime::CoretimeProviderCalls::AssignCore;
+
+ // The relay chain currently only allows `assign_core` to be called with a complete mask
+ // and only ever with increasing `begin`. The assignments must be truncated to avoid
+ // dropping that core's assignment completely.
+
+ // This shadowing of `assignment` is temporary and can be removed when the relay can accept
+ // multiple messages to assign a single core.
+ let assignment = if assignment.len() > 28 {
+ let mut total_parts = 0u16;
+ // Account for missing parts with a new `Idle` assignment at the start as
+ // `assign_core` on the relay assumes this is sorted. We'll add the rest of the
+ // assignments and sum the parts in one pass, so this is just initialized to 0.
+ let mut assignment_truncated = vec![(CoreAssignment::Idle, 0)];
+ // Truncate to first 27 non-idle assignments.
+ assignment_truncated.extend(
+ assignment
+ .into_iter()
+ .filter(|(a, _)| *a != CoreAssignment::Idle)
+ .take(27)
+ .inspect(|(_, parts)| total_parts += *parts)
+ .collect::<Vec<_>>(),
+ );
+
+ // Set the parts of the `Idle` assignment we injected at the start of the vec above.
+ assignment_truncated[0].1 = 57_600u16.saturating_sub(total_parts);
+ assignment_truncated
+ } else {
+ assignment
+ };
+
let assign_core_call =
RelayRuntimePallets::Coretime(AssignCore(core, begin, assignment, end_hint));
diff --git a/cumulus/parachains/runtimes/coretime/coretime-westend/src/coretime.rs b/cumulus/parachains/runtimes/coretime/coretime-westend/src/coretime.rs
index 865ff68d4c659fd8c324595eadf790be655f9655..86769cb2da112d1c7b37c36306216f09b90f034d 100644
--- a/cumulus/parachains/runtimes/coretime/coretime-westend/src/coretime.rs
+++ b/cumulus/parachains/runtimes/coretime/coretime-westend/src/coretime.rs
@@ -224,8 +224,6 @@ impl CoretimeInterface for CoretimeAllocator {
end_hint: Option<RCBlockNumberOf<Self>>,
) {
use crate::coretime::CoretimeProviderCalls::AssignCore;
- let assign_core_call =
- RelayRuntimePallets::Coretime(AssignCore(core, begin, assignment, end_hint));
// Weight for `assign_core` from westend benchmarks:
// `ref_time` = 10177115 + (1 * 25000000) + (2 * 100000000) + (57600 * 13932) = 937660315
@@ -233,6 +231,38 @@ impl CoretimeInterface for CoretimeAllocator {
// Add 5% to each component and round to 2 significant figures.
let call_weight = Weight::from_parts(980_000_000, 3800);
+ // The relay chain currently only allows `assign_core` to be called with a complete mask
+ // and only ever with increasing `begin`. The assignments must be truncated to avoid
+ // dropping that core's assignment completely.
+
+ // This shadowing of `assignment` is temporary and can be removed when the relay can accept
+ // multiple messages to assign a single core.
+ let assignment = if assignment.len() > 28 {
+ let mut total_parts = 0u16;
+ // Account for missing parts with a new `Idle` assignment at the start as
+ // `assign_core` on the relay assumes this is sorted. We'll add the rest of the
+ // assignments and sum the parts in one pass, so this is just initialized to 0.
+ let mut assignment_truncated = vec![(CoreAssignment::Idle, 0)];
+ // Truncate to first 27 non-idle assignments.
+ assignment_truncated.extend(
+ assignment
+ .into_iter()
+ .filter(|(a, _)| *a != CoreAssignment::Idle)
+ .take(27)
+ .inspect(|(_, parts)| total_parts += *parts)
+ .collect::<Vec<_>>(),
+ );
+
+ // Set the parts of the `Idle` assignment we injected at the start of the vec above.
+ assignment_truncated[0].1 = 57_600u16.saturating_sub(total_parts);
+ assignment_truncated
+ } else {
+ assignment
+ };
+
+ let assign_core_call =
+ RelayRuntimePallets::Coretime(AssignCore(core, begin, assignment, end_hint));
+
let message = Xcm(vec![
Instruction::UnpaidExecution {
weight_limit: WeightLimit::Unlimited,
diff --git a/prdoc/pr_6022.prdoc b/prdoc/pr_6022.prdoc
new file mode 100644
index 0000000000000000000000000000000000000000..804d46af6613b3f92d921bb8861aa1f69524fa28
--- /dev/null
+++ b/prdoc/pr_6022.prdoc
@@ -0,0 +1,14 @@
+title: '[Coretime chain] Add high assignment count mitigation to testnets'
+doc:
+- audience: Runtime User
+ description: |
+ We can handle a maximum of 28 assignments inside one XCM, while it's possible to have 80 (if a
+ region is interlaced 79 times). This can be chunked on the coretime chain side but currently the
+ relay does not support this. This PR truncates the additional assignments on Rococo and Westend
+ to mitigate this until the relay is fixed. The first 27 assignments are taken, the final 28th is
+ used to pad with idle to complete the mask. Any other assignments are dropped.
+crates:
+- name: coretime-rococo-runtime
+ bump: patch
+- name: coretime-westend-runtime
+ bump: patch