From ee87d701553abe3fa965df0bebe190376c992575 Mon Sep 17 00:00:00 2001
From: Simon Bjurek <simbj106@student.liu.se>
Date: Mon, 24 Mar 2025 10:12:23 +0100
Subject: [PATCH] added retiming step for RecursiveListScheduler
---
b_asic/scheduler.py | 76 +++++++++++++++++++++++++++++--
test/unit/test_list_schedulers.py | 15 ++++++
2 files changed, 86 insertions(+), 5 deletions(-)
diff --git a/b_asic/scheduler.py b/b_asic/scheduler.py
index b81879df..306cdccd 100644
--- a/b_asic/scheduler.py
+++ b/b_asic/scheduler.py
@@ -81,7 +81,7 @@ class Scheduler(ABC):
def _place_outputs_asap(
self, schedule: "Schedule", non_schedulable_ops: list["GraphID"] | None = []
) -> None:
- for output in schedule.sfg.find_by_type(Output):
+ for output in schedule._sfg.find_by_type(Output):
output = cast(Output, output)
source_port = cast(OutputPort, output.inputs[0].signals[0].source)
if source_port.operation.graph_id in non_schedulable_ops:
@@ -811,16 +811,12 @@ class RecursiveListScheduler(ListScheduler):
self,
sort_order: tuple[tuple[int, bool], ...],
max_resources: dict[TypeName, int] | None = None,
- max_concurrent_reads: int | None = None,
- max_concurrent_writes: int | None = None,
input_times: dict["GraphID", int] | None = None,
output_delta_times: dict["GraphID", int] | None = None,
) -> None:
super().__init__(
sort_order=sort_order,
max_resources=max_resources,
- max_concurrent_reads=max_concurrent_reads,
- max_concurrent_writes=max_concurrent_writes,
input_times=input_times,
output_delta_times=output_delta_times,
)
@@ -846,7 +842,10 @@ class RecursiveListScheduler(ListScheduler):
if self._schedule._schedule_time is None:
self._schedule.set_schedule_time(self._schedule.get_max_end_time())
+ period_bound = self._schedule._sfg.iteration_period_bound()
self._schedule.remove_delays()
+ if loops:
+ self._retime_ops(period_bound)
self._handle_dont_cares()
self._schedule.sort_y_locations_on_start_times()
self._logger.debug("--- Scheduling completed ---")
@@ -884,6 +883,73 @@ class RecursiveListScheduler(ListScheduler):
]
return [(op_id, self._deadlines[op_id]) for op_id in ready_ops]
+ def _retime_ops(self, period_bound: int) -> None:
+ # calculate the time goal
+ time_goal = period_bound
+ for type_name, amount_of_resource in self._max_resources.items():
+ if type_name in ("out", "in"):
+ continue
+ time_required = self._schedule._sfg.resource_lower_bound(
+ type_name, time_goal
+ )
+ while (
+ self._schedule._sfg.resource_lower_bound(type_name, time_required)
+ > amount_of_resource
+ ):
+ time_required += 1
+ time_goal = max(time_goal, time_required)
+
+ # retiming loop
+ time_out_counter = 100
+ while self._schedule._schedule_time > time_goal and time_out_counter > 0:
+ sorted_op_ids = sorted(
+ self._schedule._start_times,
+ key=self._schedule._start_times.get,
+ reverse=True,
+ )
+ # move all operations forward to the next valid step and check if period can be reduced
+ for op_id in sorted_op_ids:
+ op = self._schedule._sfg.find_by_id(op_id)
+ if self._schedule.forward_slack(op_id):
+ delta = 1
+ new_time = (
+ self._schedule._start_times[op_id] + delta
+ ) % self._schedule.schedule_time
+ exec_count = self._execution_times_in_time(op, new_time)
+ while exec_count >= self._remaining_resources[op.type_name()]:
+ delta += 1
+ new_time = (
+ self._schedule._start_times[op_id] + delta
+ ) % self._schedule.schedule_time
+ exec_count = self._execution_times_in_time(op, new_time)
+ if delta > self._schedule.forward_slack(op_id):
+ continue
+ self._schedule.move_operation(op_id, delta)
+
+ # adjust time if a gap exists on the right side of the schedule
+ self._schedule._schedule_time = min(
+ self._schedule._schedule_time, self._schedule.get_max_end_time()
+ )
+
+ # adjust time if a gap exists on the left side of the schedule
+ slack = min(self._schedule._start_times.values())
+ for other_op_id in sorted_op_ids:
+ op = self._schedule._sfg.find_by_id(op_id)
+ max_end_time = 0
+ op_start_time = self._schedule._start_times[other_op_id]
+ for outport in op.outputs:
+ max_end_time = max(
+ max_end_time,
+ op_start_time + cast(int, outport.latency_offset),
+ )
+ if max_end_time > self._schedule._schedule_time:
+ slack = min(slack, self._schedule.forward_slack(other_op_id))
+ for op_id in self._schedule._start_times:
+ self._schedule._start_times[op_id] -= slack
+ self._schedule._schedule_time = self._schedule._schedule_time - slack
+
+ time_out_counter -= 1
+
def _schedule_recursive_ops(self, loops: list[list["GraphID"]]) -> None:
saved_sched_time = self._schedule._schedule_time
self._schedule._schedule_time = None
diff --git a/test/unit/test_list_schedulers.py b/test/unit/test_list_schedulers.py
index edff8a5d..9dbe448c 100644
--- a/test/unit/test_list_schedulers.py
+++ b/test/unit/test_list_schedulers.py
@@ -1853,6 +1853,10 @@ class TestRecursiveListScheduler:
),
)
_validate_recreated_sfg_filter(sfg, schedule)
+ assert schedule.schedule_time == sfg.iteration_period_bound()
+ for op_id in schedule.start_times:
+ assert schedule.backward_slack(op_id) >= 0
+ assert schedule.forward_slack(op_id) >= 0
def test_direct_form_2_iir(self):
N = 3
@@ -1878,6 +1882,10 @@ class TestRecursiveListScheduler:
),
)
_validate_recreated_sfg_filter(sfg, schedule)
+ assert schedule.schedule_time == sfg.iteration_period_bound()
+ for op_id in schedule.start_times:
+ assert schedule.backward_slack(op_id) >= 0
+ assert schedule.forward_slack(op_id) >= 0
def test_large_direct_form_2_iir(self):
N = 8
@@ -1903,6 +1911,9 @@ class TestRecursiveListScheduler:
),
)
_validate_recreated_sfg_filter(sfg, schedule)
+ for op_id in schedule.start_times:
+ assert schedule.backward_slack(op_id) >= 0
+ assert schedule.forward_slack(op_id) >= 0
def test_custom_recursive_filter(self):
# Create the SFG for a digital filter (seen in an exam question from TSTE87).
@@ -1939,6 +1950,10 @@ class TestRecursiveListScheduler:
),
)
_validate_recreated_sfg_filter(sfg, schedule)
+ assert schedule.schedule_time == 4 # all slots filled with cmul executions
+ for op_id in schedule.start_times:
+ assert schedule.backward_slack(op_id) >= 0
+ assert schedule.forward_slack(op_id) >= 0
def _validate_recreated_sfg_filter(sfg: SFG, schedule: Schedule) -> None:
--
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