changeset 315e133f45df in /z/repo/gem5
details: http://repo.gem5.org/gem5?cmd=changeset;node=315e133f45df
description:
ruby: Add occupancy stats to MessageBuffers
This patch is an updated version of /r/3297.
"The most important statistic for measuring memory hierarchy
performance is
throughput, which is affected by independent variables, buffer sizing
and
communication latency. It is difficult/impossible to debug performance
issues
through series buffers without knowing which are the bottlenecks. For
finite
buffers, this patch adds statistics for the average number of messages
in the
buffer, the occupancy of the buffer slots, and number of message
stalls."
diffstat:
src/mem/ruby/network/MessageBuffer.cc | 45 +++++++++++++++++++++++++++++++++-
src/mem/ruby/network/MessageBuffer.hh | 7 ++++-
2 files changed, 49 insertions(+), 3 deletions(-)
diffs (128 lines):
diff -r 588a45268ce4 -r 315e133f45df src/mem/ruby/network/MessageBuffer.cc
--- a/src/mem/ruby/network/MessageBuffer.cc Thu Jan 19 11:58:49 2017 -0500
+++ b/src/mem/ruby/network/MessageBuffer.cc Thu Jan 19 11:58:59 2017 -0500
@@ -57,6 +57,9 @@
m_stall_msg_map.clear();
m_input_link_id = 0;
m_vnet_id = 0;
+
+ m_buf_msgs = 0;
+ m_stall_time = 0;
}
unsigned int
@@ -196,6 +199,8 @@
// Insert the message into the priority heap
m_prio_heap.push_back(message);
push_heap(m_prio_heap.begin(), m_prio_heap.end(), greater<MsgPtr>());
+ // Increment the number of messages statistic
+ m_buf_msgs++;
DPRINTF(RubyQueue, "Enqueue arrival_time: %lld, Message: %s\n",
arrival_time, *(message.get()));
@@ -207,7 +212,7 @@
}
Tick
-MessageBuffer::dequeue(Tick current_time)
+MessageBuffer::dequeue(Tick current_time, bool decrement_messages)
{
DPRINTF(RubyQueue, "Popping\n");
assert(isReady(current_time));
@@ -219,6 +224,8 @@
message->updateDelayedTicks(current_time);
Tick delay = message->getDelayedTicks();
+ m_stall_time = curTick() - message->getTime();
+
// record previous size and time so the current buffer size isn't
// adjusted until schd cycle
if (m_time_last_time_pop < current_time) {
@@ -228,6 +235,11 @@
pop_heap(m_prio_heap.begin(), m_prio_heap.end(), greater<MsgPtr>());
m_prio_heap.pop_back();
+ if (decrement_messages) {
+ // If the message will be removed from the queue, decrement the
+ // number of message in the queue.
+ m_buf_msgs--;
+ }
return delay;
}
@@ -324,7 +336,9 @@
assert(getOffset(addr) == 0);
MsgPtr message = m_prio_heap.front();
- dequeue(current_time);
+ // Since the message will just be moved to stall map, indicate that the
+ // buffer should not decrement the m_buf_msgs statistic
+ dequeue(current_time, false);
//
// Note: no event is scheduled to analyze the map at a later time.
@@ -333,6 +347,7 @@
//
(m_stall_msg_map[addr]).push_back(message);
m_stall_map_size++;
+ m_stall_count++;
}
void
@@ -362,6 +377,32 @@
.name(name() + ".not_avail_count")
.desc("Number of times this buffer did not have N slots available")
.flags(Stats::nozero);
+
+ m_buf_msgs
+ .name(name() + ".avg_buf_msgs")
+ .desc("Average number of messages in buffer")
+ .flags(Stats::nozero);
+
+ m_stall_count
+ .name(name() + ".num_msg_stalls")
+ .desc("Number of times messages were stalled")
+ .flags(Stats::nozero);
+
+ m_occupancy
+ .name(name() + ".avg_buf_occ")
+ .desc("Average occupancy of buffer capacity")
+ .flags(Stats::nozero);
+
+ m_stall_time
+ .name(name() + ".avg_stall_time")
+ .desc("Average number of cycles messages are stalled in this MB")
+ .flags(Stats::nozero);
+
+ if (m_max_size > 0) {
+ m_occupancy = m_buf_msgs / m_max_size;
+ } else {
+ m_occupancy = 0;
+ }
}
uint32_t
diff -r 588a45268ce4 -r 315e133f45df src/mem/ruby/network/MessageBuffer.hh
--- a/src/mem/ruby/network/MessageBuffer.hh Thu Jan 19 11:58:49 2017 -0500
+++ b/src/mem/ruby/network/MessageBuffer.hh Thu Jan 19 11:58:59 2017 -0500
@@ -100,7 +100,7 @@
//! Updates the delay cycles of the message at the head of the queue,
//! removes it from the queue and returns its total delay.
- Tick dequeue(Tick current_time);
+ Tick dequeue(Tick current_time, bool decrement_messages = true);
void recycle(Tick current_time, Tick recycle_latency);
bool isEmpty() const { return m_prio_heap.size() == 0; }
@@ -189,6 +189,11 @@
int m_input_link_id;
int m_vnet_id;
+
+ Stats::Average m_buf_msgs;
+ Stats::Average m_stall_time;
+ Stats::Scalar m_stall_count;
+ Stats::Formula m_occupancy;
};
Tick random_time();
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