diff options
| author | Tushar Krishna <tushar@ece.gatech.edu> | 2017-02-12 15:00:03 -0500 |
|---|---|---|
| committer | Tushar Krishna <tushar@ece.gatech.edu> | 2017-02-12 15:00:03 -0500 |
| commit | 1be05afa068c6898ae13c6207beebb2a700a8678 (patch) | |
| tree | 344621e26c68ed7d1bbdc497aedf460c7bffeb13 /src/mem | |
| parent | f3643c8a60571604466bc78cc404fbfec704a1cf (diff) | |
| download | gem5-1be05afa068c6898ae13c6207beebb2a700a8678.tar.xz | |
ruby: fix round robin arbiter in garnet2.0
The rr arbiter pointer in garnet was getting updated on every request,
even if there is no grant. This was leading to a huge variance in wait
time at a router at high injection rates.
This patch corrects it to update upon a grant.
Diffstat (limited to 'src/mem')
| -rw-r--r-- | src/mem/ruby/network/garnet2.0/SwitchAllocator.cc | 22 |
1 files changed, 11 insertions, 11 deletions
diff --git a/src/mem/ruby/network/garnet2.0/SwitchAllocator.cc b/src/mem/ruby/network/garnet2.0/SwitchAllocator.cc index 7916802a5..4619b0b8a 100644 --- a/src/mem/ruby/network/garnet2.0/SwitchAllocator.cc +++ b/src/mem/ruby/network/garnet2.0/SwitchAllocator.cc @@ -116,13 +116,6 @@ SwitchAllocator::arbitrate_inports() for (int inport = 0; inport < m_num_inports; inport++) { int invc = m_round_robin_invc[inport]; - // Select next round robin vc candidate within valid vnet - int next_round_robin_invc = invc; - next_round_robin_invc++; - if (next_round_robin_invc >= m_num_vcs) - next_round_robin_invc = 0; - m_round_robin_invc[inport] = next_round_robin_invc; - for (int invc_iter = 0; invc_iter < m_num_vcs; invc_iter++) { if (m_input_unit[inport]->need_stage(invc, SA_, @@ -142,6 +135,12 @@ SwitchAllocator::arbitrate_inports() m_input_arbiter_activity++; m_port_requests[outport][inport] = true; m_vc_winners[outport][inport]= invc; + + // Update Round Robin pointer + m_round_robin_invc[inport]++; + if (m_round_robin_invc[inport] >= m_num_vcs) + m_round_robin_invc[inport] = 0; + break; // got one vc winner for this port } } @@ -175,10 +174,6 @@ SwitchAllocator::arbitrate_outports() // Independent arbiter at each output port for (int outport = 0; outport < m_num_outports; outport++) { int inport = m_round_robin_inport[outport]; - m_round_robin_inport[outport]++; - - if (m_round_robin_inport[outport] >= m_num_inports) - m_round_robin_inport[outport] = 0; for (int inport_iter = 0; inport_iter < m_num_inports; inport_iter++) { @@ -256,6 +251,11 @@ SwitchAllocator::arbitrate_outports() // remove this request m_port_requests[outport][inport] = false; + // Update Round Robin pointer + m_round_robin_inport[outport]++; + if (m_round_robin_inport[outport] >= m_num_inports) + m_round_robin_inport[outport] = 0; + break; // got a input winner for this outport } |