Congestion-Aware Initial Accumulated Cost #3031

soheilshahrouz · 2025-05-10T21:46:20Z

This PR adds a new option to bias routing away from congested channels during early iterations by adjusting the initial accumulated cost based on estimated CHANX/CHANY utilization.

…ted_routing_util()

…e options

… t_route_opts check if ExtendedMapLookahead fails

soheilshahrouz · 2025-05-11T00:06:34Z

To-do list

compute channel widths by iterating over RR nodes ---> done
support 3d ---> CHANX/CHANY utilization for all layers are computed. CHANX nodes that represent vertical connection are mistakenly initilized with acc_cost of the CHANX at that location.

soheilshahrouz · 2025-05-12T15:03:41Z

titan_quick_qor

channel width	place_time	wl	cpd	route_time	pack_time	heap_pops	total_swaps
300	1.0007	0.9991	0.9965	0.9993	0.9950	1.0067	1
270	1.0054	0.9984	1.0047	0.9615	0.9965	0.9914	1
250	0.9876	0.9981	1.0031	0.8403	0.9924	0.8510	1

In experiments with a channel width of 250, bitcoin_miner failed for both the master branch and this branch.

…licts

…g over rr nodes

vaughnbetz

Needs lots of testing to be on by default:
Koios QoR
VTR QoR on binary search and final routing at 1.3Wmin
3D FPGAs work / have reasonable QoR.

Follow on possible work: check if drawing depends on arch file channels -> update if needed.

libs/librrgraph/src/base/rr_graph_type.h

libs/librrgraph/src/base/rr_node_types.h

vpr/src/base/read_options.cpp

vpr/src/base/stats.cpp

vpr/src/place/net_cost_handler.h

vpr/src/place/net_cost_handler.cpp

vpr/src/place/placer.cpp

vpr/src/route/route_common.cpp

vpr/src/route/router_lookahead/router_lookahead.h

vaughnbetz · 2025-05-26T23:06:24Z

Could use this as an opportunity to make

Drawing use channel widths calculated from the rr-graph (not the arch file) so it draws properly with a read-in rr-graph. See

vtr-verilog-to-routing/vpr/src/draw/draw.cpp

Line 581 in ea896e2

j += device_ctx.chan_width.y_list[i] + 1; /* N wires need N+1 units of space */
Placement cost (linear congestion / scaling of wiring by average channel width over bb) also respond to the rr-graph, not the arch file.

vaughnbetz · 2025-05-26T23:09:08Z

Probably moving this code out of stats.cpp would also be good -- it'll become more fundamental.

…_cong

…ndler::estimate_routing_chan_util()

…_cong

soheilshahrouz · 2025-05-30T16:28:07Z

VTR benchmarks minimum channel width search

Metric	feature.txt
vtr_flow_elapsed_time	1.109599868
odin_synth_time
parmys_synth_time	0.9942209611
abc_depth	1
abc_synth_time	1.001840561
num_clb	1
num_memories	1
num_mult	1
max_vpr_mem	0.9914816969
num_pre_packed_blocks	1
num_post_packed_blocks	1
device_grid_tiles	1
pack_time	1.000728945
placed_wirelength_est	1
place_time	1.025983213
placed_CPD_est	1
min_chan_width	0.9906351292
routed_wirelength	1.002237975
min_chan_width_route_time	1.352100907
crit_path_routed_wirelength	1.001354999
critical_path_delay	1.000111178
geomean_nonvirtual_intradomain_critical_path_delay	1.000111178
crit_path_route_time	0.9794380194

Minimum channel width was reduced in two circuits.

soheilshahrouz · 2025-05-30T17:16:52Z

VTR benchmarks
1.3minW

circuit	route_time	cpd	heap_pops	wl	place_time	pack_time
mcml.v	0.9625	0.9999531016	1.019235354	1.000281936	0.9766849315	1.001701838
LU32PEEng.v	0.9503321734	1.000014647	0.990690786	1.00014595	0.9954708105	0.9987463762
bgm.v	0.9737302977	0.9996530479	0.997730871	1.000230386	1.023058997	1.002453988
LU8PEEng.v	1.014973262	1.000074797	1.00165337	0.9988697785	1.0022553	0.9980750722
arm_core.v	1	1.000592746	0.9855161027	0.9969095411	1.004594181	1.045816253
stereovision2.v	1.005747126	0.9996107903	1.000784028	0.9993899826	1.076231263	1
stereovision1.v	1.088560886	1.00187781	1.121788749	1.00002572	1.027617952	0.9646504321

vaughnbetz · 2025-05-30T17:44:52Z

Looks good, thanks. We should get koios as well, since this is a big change.

soheilshahrouz · 2025-06-01T18:24:15Z

W=300

circuit	CPD	WL	route_time	heap_pops
tpu_like.small.os.v	1	1	1.015254237	1
tpu_like.small.ws.v	1	1	1.007668712	1
dla_like.small.v	1	0.999768608	1.018815717	1.004269293
bnn.v	1	0.9994662975	1.009292352	1.002568516
attention_layer.v	1	1	1.010739857	1
conv_layer_hls.v	1	1	0.9164619165	1
conv_layer.v	1	0.9993863978	1.053030303	1.00142193
eltwise_layer.v	1	0.9999351936	1.01025641	0.9879354833
robot_rl.v	1	1	0.9909090909	1
reduction_layer.v	1	1	0.9980430528	1
spmv.v	1	1	1.015789474	1
softmax.v	1	1	1.006349206	1
lenet.v	1.039334614	0.9979187016	1.005524862	0.9996246427
clstm_like.small.v	1	1	1.01551481	1
clstm_like.medium.v	0.9050457455	1.001017806	1.082175466	1.023845394
clstm_like.large.v	0.9523361003	1.000231865	0.974962828	0.9789848833
lstm.v	1	1	1.010317256	1
gemm_layer.v	0.8776401523	1.002186012	0.9898989899	1.013215695
tpu_like.large.os.v	1	1	1.0078075	1
tpu_like.large.ws.v	0.9912466445	0.9995306955	1.050833995	1.000956747
tdarknet_like.large.v	1	1	1.033892216	1
dla_like.medium.v	1	0.9998589942	1.004281637	0.994174936
bwave_like.float.small.v	1.020427253	1.000608795	0.9642172524	0.9816747451
bwave_like.fixed.small.v	1	1	1.013428827	1
dnnweaver.v	0.9881222569	1.001165979	0.9958448753	1.027681813
tdarknet_like.small.v	1	1	1.010583283	1
bwave_like.float.large.v	0.9734685948	1.001004839	0.9627392414	0.961273596
bwave_like.fixed.large.v	1	1.001696565	1.037675234	1.061526364
dla_like.large.v	0.9755507261	1.000620627	1.000162533	0.9959337593
proxy.1.v	1	0.9999891434	1.009653311	0.9993780357
proxy.2.v	1	1.000104018	0.9421366655	0.9980725353
proxy.3.v	1	1.000798333	0.9704296935	0.9980512289
proxy.4.v	1.009819358	1.000263529	1.012186732	1.009834591
proxy.5.v	1	1	0.9941634241	1
proxy.6.v	1	0.9998606597	1.00491763	1.00369854
proxy.7.v	1	1.000165903	1.00448682	1.013426537
proxy.8.v	1	0.9994262478	0.9944341373	0.9971751271
geomean	0.9927835526	1.000135276	1.003915663	1.001479038

soheilshahrouz · 2025-06-03T18:01:47Z

vtr_reg_nightly_test7/3d_sb_titan_other_auto_bb

circuit	CPD	WL	route_time	heap_pops
carpat_stratixiv_arch_timing.blif	1.00	1.00	1.02	1.03
CH_DFSIN_stratixiv_arch_timing.blif	1.00	1.00	1.00	1.00
CHERI_stratixiv_arch_timing.blif	1.00	1.00	1.05	1.02
EKF-SLAM_Jacobians_stratixiv_arch_timing.blif	1.00	1.00	1.04	1.03
fir_cascade_stratixiv_arch_timing.blif	1.00	1.00	1.01	1.00
jacobi_stratixiv_arch_timing.blif	1.00	1.00	1.07	1.12
JPEG_stratixiv_arch_timing.blif	1.00	1.00	1.00	1.01
leon2_stratixiv_arch_timing.blif	1.00	1.00	0.96	0.93
leon3mp_stratixiv_arch_timing.blif	1.00	1.00	1.01	1.01
MCML_stratixiv_arch_timing.blif	1.00	1.00	1.02	1.00
MMM_stratixiv_arch_timing.blif	1.00	1.00	1.05	1.00
radar20_stratixiv_arch_timing.blif	1.00	1.00	1.00	1.00
random_stratixiv_arch_timing.blif	1.00	1.00	1.01	1.00
Reed_Solomon_stratixiv_arch_timing.blif	1.00	1.00	1.01	1.00
smithwaterman_stratixiv_arch_timing.blif	1.00	1.00	1.01	1.00
stap_steering_stratixiv_arch_timing.blif	1.00	1.00	1.00	1.00
sudoku_check_stratixiv_arch_timing.blif	1.00	1.00	1.00	1.01
SURF_desc_stratixiv_arch_timing.blif	1.00	1.00	0.98	1.01
ucsb_152_tap_fir_stratixiv_arch_timing.blif	1.00	1.00	1.04	1.00
uoft_raytracer_stratixiv_arch_timing.blif	1.00	1.00	1.03	1.04
wb_conmax_stratixiv_arch_timing.blif	1.00	1.00	0.99	1.00
picosoc_stratixiv_arch_timing.blif	1.00	1.00	1.02	1.00
murax_stratixiv_arch_timing.blif	1.00	1.00	1.04	1.00
geomean	1.00	1.00	1.01	1.01

soheilshahrouz · 2025-06-04T20:12:15Z

vtr_reg_nightly_test7/3d_cb_titan_other_auto_bb

circuit	CPD	WL	route_time	heap_pops
carpat_stratixiv_arch_timing.blif	1.00	1.00	1.00	0.99
CH_DFSIN_stratixiv_arch_timing.blif	1.00	1.00	1.00	1.00
CHERI_stratixiv_arch_timing.blif	1.00	1.00	1.00	1.01
EKF-SLAM_Jacobians_stratixiv_arch_timing.blif	1.00	1.00	1.11	1.15
fir_cascade_stratixiv_arch_timing.blif	1.00	1.00	1.02	1.00
jacobi_stratixiv_arch_timing.blif	1.00	1.00	1.03	1.01
JPEG_stratixiv_arch_timing.blif	1.00	1.00	1.00	1.00
leon2_stratixiv_arch_timing.blif	1.00	1.00	1.02	1.01
leon3mp_stratixiv_arch_timing.blif	1.00	1.00	0.98	0.99
MCML_stratixiv_arch_timing.blif	1.00	1.00	1.01	1.00
MMM_stratixiv_arch_timing.blif	1.00	1.00	1.02	0.99
radar20_stratixiv_arch_timing.blif	1.00	1.00	1.00	1.00
random_stratixiv_arch_timing.blif	1.00	1.00	1.00	1.00
Reed_Solomon_stratixiv_arch_timing.blif	1.00	1.00	1.01	1.00
smithwaterman_stratixiv_arch_timing.blif	1.00	1.00	1.01	1.00
stap_steering_stratixiv_arch_timing.blif	1.00	1.00	0.99	1.00
sudoku_check_stratixiv_arch_timing.blif	1.00	1.00	1.00	0.99
SURF_desc_stratixiv_arch_timing.blif	1.00	1.00	1.04	1.03
ucsb_152_tap_fir_stratixiv_arch_timing.blif	1.00	1.00	1.00	1.00
uoft_raytracer_stratixiv_arch_timing.blif	1.00	1.00	0.99	1.01
wb_conmax_stratixiv_arch_timing.blif	1.00	1.00	0.98	1.00
picosoc_stratixiv_arch_timing.blif	1.00	1.00	0.99	1.00
murax_stratixiv_arch_timing.blif	1.00	1.00	1.02	1.00
geomean	1.00	1.00	1.01	1.01

soheilshahrouz · 2025-06-05T15:43:59Z

vtr_reg_nightly_test7/vtr_reg_qor_large_run_flat

Metric	feature.txt
vtr_flow_elapsed_time	1.043
odin_synth_time
parmys_synth_time	1.038
abc_depth	1
abc_synth_time	1.025
num_clb	1
num_memories	1
num_mult	1
max_vpr_mem	1.003
num_pre_packed_blocks	1
num_post_packed_blocks	1
device_grid_tiles	1
pack_time	1.005
placed_wirelength_est	1
place_time	1.024
placed_CPD_est	1
routed_wirelength	1.011
critical_path_delay	0.993
geomean_nonvirtual_intradomain_critical_path_delay	0.993
crit_path_route_time	1.049

soheilshahrouz · 2025-06-05T16:10:48Z

@vaughnbetz
I added QoR for flat routing and 3D. This PR is ready to merge

soheilshahrouz added 21 commits May 1, 2025 16:19

enum class e_route_type

f76808d

add estimate_routing_chann_util()

a9435b4

add set_estimated_routing_util()

6a03592

add empty() to prefix sum class

823c1a0

const reference

3208425

add chan_util_threshold and congestion_weight arguments to set_estima…

f28832e

…ted_routing_util()

implemented channel congestion factoring in map lookahead

b68b529

call set_estimated_routing_util() at the end of placement

93b1d03

add cmd line options for router lookahead congestion related params

177f73c

correct x_factor in congestion estimate of map lookahead

0c148d7

initialize acc_cost based on post-placement channel util estimate

21add30

initialize chan_util_weight and chan_util_threshold with some cmd lin…

30e0796

…e options

init acc_cost with channel util info only if such info is availale

38e748f

Merge branch 'master' into temp_lookahead_chan_cong

808b2ef

document empty() method for prefix sum classes

133c3de

move t_rr_node_route_inf from vpr_types.h to rr_node_types.h

56e8ee5

add doxygen comment for NetCostHandler::estimate_routing_chann_util()

d6a8222

remove dead code in Placer::copy_locs_to_global_state()

dcf76f2

move chan_util_threshold and chan_util_weight from routing context to…

83813fa

… t_route_opts check if ExtendedMapLookahead fails

remove changes made to routerlookahead

3ca5542

make format

c36bfb9

github-actions bot added VPR VPR FPGA Placement & Routing Tool lang-cpp C/C++ code libvtrutil labels May 10, 2025

soheilshahrouz added 2 commits May 10, 2025 19:07

make get_adjusted_rr_position() static again

49c0c98

macro --> static constexpr

167d8da

soheilshahrouz added 2 commits May 12, 2025 11:18

Merge branch 'master' into temp_lookahead_chan_cong and resolve confi…

468be05

…licts

add calculate_channel_width() that computes channel width by iteratin…

9d64010

…g over rr nodes

soheilshahrouz changed the title ~~[WIP] Initialize acc_cost with post-placement channel utilization estimate~~ Congestion-Aware Initial Accumulated Cost May 16, 2025

soheilshahrouz added 4 commits May 19, 2025 17:56

Merge branch 'master' into temp_lookahead_chan_cong

a1b76f5

Merge branch 'master' into temp_lookahead_chan_cong

44dbc4f

pragma once instead header guards

08507dc

remove clock_fwd.h

a2dc76c

soheilshahrouz requested a review from vaughnbetz May 20, 2025 21:18

vaughnbetz requested changes May 26, 2025

View reviewed changes

soheilshahrouz added 11 commits May 27, 2025 14:35

Merge remote-tracking branch 'origin/master' into temp_lookahead_chan…

079e8c1

…_cong

incerement channel width counters by node capacity

f5c866a

rename estimate_routing_chann_util(() to estimate_routing_chan_util()

af7950c

doxygen comment for e_route_type and improve comments for NetCostHa…

bc7f9d1

…ndler::estimate_routing_chan_util()

doxygen comment for t_rr_rc_data

20dd3f8

move t_rr_node_route_inf from rr_node_type.h to route_commmon.h

26e1017

make format

0837e07

Merge remote-tracking branch 'origin/master' into temp_lookahead_chan…

27553a7

…_cong

fix compilation error when server feature is enabled

9e41b34

fix compilation error on savi3

546980b

fix remaining compiliation errors on savi3

7fff850

soheilshahrouz added 2 commits June 1, 2025 14:45

rename copy_locs_to_global_state() to update_global_state()

9a1ef9d

add comment to comp_initial_acc_cost()

d7d189b

Congestion-Aware Initial Accumulated Cost #3031

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