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mem-ruby: fine tunning SimpleNetwork buffers

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If physical_vnets_channels is set we adjust the link buffer sizes and
the max_dequeue_rate in order to achieve the expected maximum throughput
assuming a fully pipelined link, i.e., throughput of 1 msg per cycle
per channel (assuming the channels width matches the protocol
logical message size, otherwise maximum throughput may be smaller).

JIRA: https://gem5.atlassian.net/browse/GEM5-920

Change-Id: Id99ab745ed54686d8ffcc630d622fb07ac0fc352
Signed-off-by: Tiago Mück <tiago.muck@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/41863
Reviewed-by: Meatboy 106 <garbage2collector@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
This commit is contained in:
Tiago Mück
2020-09-30 16:44:46 -05:00
committed by Tiago Muck
parent 986e7b90d3
commit b476d7c1d3
2 changed files with 36 additions and 17 deletions
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23
src/mem/ruby/network/simple/SimpleLink.py
View File

@@ -63,12 +63,29 @@ class SimpleIntLink(BasicIntLink):
if len(self.buffers) > 0:
fatal("User should not manually set links' \
in_buffers or out_buffers")
# Note that all SimpleNetwork MessageBuffers are currently ordered
# The network needs number_of_virtual_networks buffers per
# in and out port
buffers = []
for i in range(int(network.number_of_virtual_networks)):
buffers.append(MessageBuffer(ordered = True,
buffer_size = network.vnet_buffer_size(i)))
buffers.append(MessageBuffer(ordered = True))
# If physical_vnets_channels is set we adjust the buffer sizes and
# the max_dequeue_rate in order to achieve the expected thoughput
# assuming a fully pipelined link, i.e., throughput of 1 msg per cycle
# per channel (assuming the channels width matches the protocol
# logical message size, otherwise maximum thoughput may be smaller).
# In MessageBuffer, an entry occupied by a dequeued message at cycle
# X will available for enqueuing another message at cycle X+1. So
# for a 1 cy enqueue latency, 2 entries are needed. For any latency,
# the size should be at least latency+1.
if len(network.physical_vnets_channels) != 0:
assert(len(network.physical_vnets_channels) == \
int(network.number_of_virtual_networks))
for i in range(int(network.number_of_virtual_networks)):
buffers[i].buffer_size = \
network.physical_vnets_channels[i] * (self.latency + 1)
buffers[i].max_dequeue_rate = \
network.physical_vnets_channels[i]
self.buffers = buffers

30
src/mem/ruby/network/simple/SimpleNetwork.py
View File

@@ -63,18 +63,6 @@ class SimpleNetwork(RubyNetwork):
"Only valid when physical_vnets_channels is set. This overrides the"
"bandwidth_factor parameter set for the individual links.")
def vnet_buffer_size(self, vnet):
"""
Gets the size of the message buffers associated to a vnet
If physical_vnets_channels is set we just multiply the size of the
buffers as SimpleNetwork does not actually creates multiple physical
channels per vnet.
"""
if len(self.physical_vnets_channels) == 0:
return self.buffer_size
else:
return self.buffer_size * self.physical_vnets_channels[vnet]
def setup_buffers(self):
# Setup internal buffers for links and routers
for link in self.int_links:
@@ -128,8 +116,22 @@ class Switch(BasicRouter):
"Routing strategy to be used")
def setup_buffers(self, network):
def vnet_buffer_size(vnet):
"""
Gets the size of the message buffers associated to a vnet
If physical_vnets_channels is set we just multiply the size of the
buffers as SimpleNetwork does not actually creates multiple phy
channels per vnet.
"""
if len(network.physical_vnets_channels) == 0:
return network.buffer_size
else:
return network.buffer_size * \
network.physical_vnets_channels[vnet]
if len(self.port_buffers) > 0:
fatal("User should not manually set routers' port_buffers")
router_buffers = []
# Add message buffers to routers at the end of each
# unidirectional internal link
@@ -137,7 +139,7 @@ class Switch(BasicRouter):
if link.dst_node == self:
for i in range(int(network.number_of_virtual_networks)):
router_buffers.append(SwitchPortBuffer(
buffer_size = network.vnet_buffer_size(i)))
buffer_size = vnet_buffer_size(i)))
# Add message buffers to routers for each external link connection
for link in network.ext_links:
@@ -145,6 +147,6 @@ class Switch(BasicRouter):
if link.int_node == self:
for i in range(int(network.number_of_virtual_networks)):
router_buffers.append(SwitchPortBuffer(
buffer_size = network.vnet_buffer_size(i)))
buffer_size = vnet_buffer_size(i)))
self.port_buffers = router_buffers