Andreas Sandberg has submitted this change and it was merged. (
https://gem5-review.googlesource.com/2600 )
Change subject: sim: Handle cases where Drainable::resume() creates objects
......................................................................
sim: Handle cases where Drainable::resume() creates objects
There are cases where Drainable objects need to create new objects in
Drainable::resume(). In such cases, the local drain state will be
inherited from the DrainManager. We currently set the state to Running
as soon as we start resuming the simulator. This means that new
objects are created in the Running state rather than the Drained
state, which the resume code assumes. Depending on the traversal order
in DrainManager::resume(), this sometimes triggers a panic because the
object being resumed is in the wrong state.
This change introduces a new drain state, Resuming, that the
DrainManager enters as soon as it starts resuming the
simulator. Objects that are created while resuming are created in this
state. Such objects are then resumed in a subsequent pass over the
list of Drainable objects that need to be resumed. Once all objects
have been resumed, the simulator enters the Running state.
Change-Id: Ieee8645351ffbdec477e9cd2ff86fc795e459617
Signed-off-by: Andreas Sandberg <[email protected]>
Reviewed-by: Curtis Dunham <[email protected]>
Reviewed-on: https://gem5-review.googlesource.com/2600
Reviewed-by: Jason Lowe-Power <[email protected]>
Reviewed-by: Weiping Liao <[email protected]>
---
M src/sim/drain.cc
M src/sim/drain.hh
2 files changed, 51 insertions(+), 8 deletions(-)
Approvals:
Jason Lowe-Power: Looks good to me, approved
Weiping Liao: Looks good to me, but someone else must approve
Andreas Sandberg: Looks good to me, approved
diff --git a/src/sim/drain.cc b/src/sim/drain.cc
index bb8abd7..e920ee7 100644
--- a/src/sim/drain.cc
+++ b/src/sim/drain.cc
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2012, 2015 ARM Limited
+ * Copyright (c) 2012, 2015, 2017 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
@@ -101,14 +101,33 @@
"Resuming a system that isn't fully drained, this is untested
and "
"likely to break\n");
+ panic_if(_state == DrainState::Resuming,
+ "Resuming a system that is already trying to resume. This
should "
+ "never happen.\n");
+
panic_if(_count != 0,
"Resume called in the middle of a drain cycle. %u objects "
"left to drain.\n", _count);
- DPRINTF(Drain, "Resuming %u objects.\n", drainableCount());
+ // At this point in time the DrainManager and all objects will be
+ // in the the Drained state. New objects (i.e., objects created
+ // while resuming) will inherit the Resuming state from the
+ // DrainManager, which means we have to resume objects until all
+ // objects are in the Running state.
+ _state = DrainState::Resuming;
+
+ do {
+ DPRINTF(Drain, "Resuming %u objects.\n", drainableCount());
+ for (auto *obj : _allDrainable) {
+ if (obj->drainState() != DrainState::Running) {
+ assert(obj->drainState() == DrainState::Drained ||
+ obj->drainState() == DrainState::Resuming);
+ obj->dmDrainResume();
+ }
+ }
+ } while (!allInState(DrainState::Running));
+
_state = DrainState::Running;
- for (auto *obj : _allDrainable)
- obj->dmDrainResume();
}
void
@@ -154,6 +173,17 @@
_allDrainable.erase(o);
}
+bool
+DrainManager::allInState(DrainState state) const
+{
+ for (const auto *obj : _allDrainable) {
+ if (obj->drainState() != state)
+ return false;
+ }
+
+ return true;
+}
+
size_t
DrainManager::drainableCount() const
{
@@ -189,7 +219,8 @@
void
Drainable::dmDrainResume()
{
- panic_if(_drainState != DrainState::Drained,
+ panic_if(_drainState != DrainState::Drained &&
+ _drainState != DrainState::Resuming,
"Trying to resume an object that hasn't been drained\n");
_drainState = DrainState::Running;
diff --git a/src/sim/drain.hh b/src/sim/drain.hh
index 6639466..7ff1d6e 100644
--- a/src/sim/drain.hh
+++ b/src/sim/drain.hh
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2012, 2015 ARM Limited
+ * Copyright (c) 2012, 2015, 2017 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
@@ -58,7 +58,11 @@
* all objects have entered the Drained state.
*
* Before resuming simulation, the simulator calls resume() to
- * transfer the object to the Running state.
+ * transfer the object to the Running state. This in turn results in a
+ * call to drainResume() for all Drainable objects in the
+ * simulator. New Drainable objects may be created while resuming. In
+ * such cases, the new objects will be created in the Resuming state
+ * and later resumed.
*
* \note Even though the state of an object (visible to the rest of
* the world through Drainable::getState()) could be used to determine
@@ -68,7 +72,8 @@
enum class DrainState {
Running, /** Running normally */
Draining, /** Draining buffers pending serialization/handover */
- Drained /** Buffers drained, ready for serialization/handover */
+ Drained, /** Buffers drained, ready for serialization/handover */
+ Resuming, /** Transient state while the simulator is resuming */
};
#endif
@@ -152,6 +157,12 @@
void unregisterDrainable(Drainable *obj);
private:
+ /**
+ * Helper function to check if all Drainable objects are in a
+ * specific state.
+ */
+ bool allInState(DrainState state) const;
+
/**
* Thread-safe helper function to get the number of Drainable
* objects in a system.
@@ -261,6 +272,7 @@
switch (_drainState) {
case DrainState::Running:
case DrainState::Drained:
+ case DrainState::Resuming:
return;
case DrainState::Draining:
_drainState = DrainState::Drained;
--
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Gerrit-Project: public/gem5
Gerrit-Branch: master
Gerrit-MessageType: merged
Gerrit-Change-Id: Ieee8645351ffbdec477e9cd2ff86fc795e459617
Gerrit-Change-Number: 2600
Gerrit-PatchSet: 2
Gerrit-Owner: Andreas Sandberg <[email protected]>
Gerrit-Reviewer: Andreas Sandberg <[email protected]>
Gerrit-Reviewer: Jason Lowe-Power <[email protected]>
Gerrit-Reviewer: Rahul Thakur <[email protected]>
Gerrit-Reviewer: Weiping Liao <[email protected]>
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