Running into error "[ERROR GRT-0119] Routing congestion too high"

[dalyles]

When I'm trying to do runs, I occasionally run into this error message at the bottom of this snapshot:

Elapsed time: 14:45.25[h:]min:sec. CPU time: user 884.58 sys 0.25 (99%). Peak memory: 206544KB.
(/usr/bin/time -f 'Elapsed time: %E[h:]min:sec. CPU time: user %U sys %S (%P). Peak memory: %MKB.' /home/dlyles/OpenROAD-flow-scripts/tools/install/OpenROAD/bin/openroad -exit -no_init  ./scripts/fillcell.tcl -metrics ./logs/sky130hs/picorv32/base/4_2_cts_fillcell.json) 2>&1 | tee ./logs/sky130hs/picorv32/base/4_2_cts_fillcell.log
OpenROAD v2.0-9070-gbb341ffb9 
This program is licensed under the BSD-3 license. See the LICENSE file for details.
Components of this program may be licensed under more restrictive licenses which must be honored.
[INFO DPL-0001] Placed 6286 filler instances.
Elapsed time: 0:01.26[h:]min:sec. CPU time: user 1.20 sys 0.06 (100%). Peak memory: 153060KB.
cp results/sky130hs/picorv32/base/4_2_cts_fillcell.odb results/sky130hs/picorv32/base/4_cts.odb
(/usr/bin/time -f 'Elapsed time: %E[h:]min:sec. CPU time: user %U sys %S (%P). Peak memory: %MKB.' /home/dlyles/OpenROAD-flow-scripts/tools/install/OpenROAD/bin/openroad -exit -no_init  ./scripts/global_route.tcl -metrics ./logs/sky130hs/picorv32/base/5_1_grt.json) 2>&1 | tee ./logs/sky130hs/picorv32/base/5_1_grt.log
OpenROAD v2.0-9070-gbb341ffb9 
This program is licensed under the BSD-3 license. See the LICENSE file for details.
Components of this program may be licensed under more restrictive licenses which must be honored.
[INFO GRT-0020] Min routing layer: met1
[INFO GRT-0021] Max routing layer: met5
[INFO GRT-0022] Global adjustment: 0%
[INFO GRT-0023] Grid origin: (0, 0)
[INFO GRT-0043] No OR_DEFAULT vias defined.
[INFO GRT-0088] Layer li1     Track-Pitch = 0.4800  line-2-Via Pitch: 0.3400
[INFO GRT-0088] Layer met1    Track-Pitch = 0.3700  line-2-Via Pitch: 0.3400
[INFO GRT-0088] Layer met2    Track-Pitch = 0.4800  line-2-Via Pitch: 0.3500
[INFO GRT-0088] Layer met3    Track-Pitch = 0.7400  line-2-Via Pitch: 0.6150
[INFO GRT-0088] Layer met4    Track-Pitch = 0.9600  line-2-Via Pitch: 1.0400
[INFO GRT-0088] Layer met5    Track-Pitch = 3.3300  line-2-Via Pitch: 3.1100
[INFO GRT-0019] Found 75 clock nets.
[INFO GRT-0001] Minimum degree: 2
[INFO GRT-0002] Maximum degree: 145
[INFO GRT-0003] Macros: 0
[INFO GRT-0004] Blockages: 1214

[INFO GRT-0053] Routing resources analysis:
          Routing      Original      Derated      Resource
Layer     Direction    Resources     Resources    Reduction (%)
---------------------------------------------------------------
li1        Vertical            0             0          0.00%
met1       Horizontal      75411         37990          49.62%
met2       Vertical        59535         39051          34.41%
met3       Horizontal      35721         23172          35.13%
met4       Vertical        23814         11470          51.84%
met5       Horizontal       7938          3969          50.00%
---------------------------------------------------------------

[INFO GRT-0101] Running extra iterations to remove overflow.
[INFO GRT-0103] Extra Run for hard benchmark.
[INFO GRT-0197] Via related to pin nodes: 68391
[INFO GRT-0198] Via related Steiner nodes: 3466
[INFO GRT-0199] Via filling finished.
[INFO GRT-0111] Final number of vias: 114077
[INFO GRT-0112] Final usage 3D: 536326
[ERROR GRT-0119] Routing congestion too high. Check the congestion heatmap in the GUI and load ./reports/sky130hs/picorv32/base/congestion.rpt in the DRC viewer.
Error: global_route.tcl, 21 GRT-0119

Does anyone have any guidance in how to resolve this issue? I'm using the autotuner instead of make and the runs end up being incomplete. I'll provide more details upon request.

Thanks!

[vijayank88]

@dalyles
Is AutoTuner Best parameters found tag have complete results or not?

[dalyles]

To answer your question, it does complete when the process goes through (14 hours) however, when it comes to checking the *-or folder, it's not complete, it terminates somewhere around the placement stage.

[vijayank88]

Share your autotuner config.json used to run the flow.

[dalyles]

You mean this?

export DESIGN_NAME = picorv32
export PLATFORM    = sky130hs

export VERILOG_FILES = ./designs/src/$(DESIGN_NAME)/picorv32.v
export SDC_FILE      = ./designs/$(PLATFORM)/$(DESIGN_NAME)/constraint.sdc
#export FASTROUTE_TCL = ./fastroute.tcl
export ABC_AREA      = 1

# Adders degrade GCD
export ADDER_MAP_FILE :=

export CORE_UTILIZATION ?= 55
export PLACE_DENSITY_LB_ADDON = 0.20
export TNS_END_PERCENT = 100

[vijayank88]

Sorry... i need autotuner.json

[dalyles]

Here it is:

{
    "_SDC_FILE_PATH": "constraint.sdc",
    "_SDC_CLK_PERIOD": {
        "type": "float",
        "minmax": [
            3.6,
            3.6
        ],
        "step": 0
    },
    "CORE_UTILIZATION": {
        "type": "int",
        "minmax": [
            60,
            100
        ],
        "step": 1
    },
    "CORE_ASPECT_RATIO": {
        "type": "float",
        "minmax": [
            1.0,
            2.5
        ],
        "step": 0
    },
    "CORE_MARGIN": {
        "type": "int",
        "minmax": [
            2,
            5
        ],
        "step": 0
    },
    "CAP_MARGIN": {
        "type":"int",
        "minmax": [
            5,
            100
        ],
        "step": 1
    },
    "SLEW_MARGIN": {
        "type":"int",
        "minmax": [
            5,
            100
        ],
        "step": 1
    },
    "CELL_PAD_IN_SITES_GLOBAL_PLACEMENT": {
        "type": "int",
        "minmax": [
            0,
            5
        ],
        "step": 1
    },
    "CELL_PAD_IN_SITES_DETAIL_PLACEMENT": {
        "type": "int",
        "minmax": [
            0,
            5
        ],
        "step": 1
    },
    "_FR_LAYER_ADJUST": {
        "type": "float",
        "minmax": [
            0.1,
            0.7
        ],
        "step": 0
    },
    "PLACE_DENSITY_LB_ADDON": {
        "type": "float",
        "minmax": [
            0.0,
            0.99
        ],
        "step": 0
    },
    "_PINS_DISTANCE": {
        "type": "int",
        "minmax": [
            1,
            4
        ],
        "step": 1
    },
    "CTS_CLUSTER_SIZE": {
        "type": "int",
        "minmax": [
            10,
            200
        ],
        "step": 1
    },
    "CTS_CLUSTER_DIAMETER": {
        "type": "int",
        "minmax": [
            20,
            400
        ],
        "step": 1
    },
    "_FR_FILE_PATH": "../../../platforms/sky130hs/fastroute.tcl",
    "_FR_GR_OVERFLOW": {
        "type": "int",
        "minmax": [
            1,
            1
        ],
        "step": 0
    }
}

[maliberty]

If the autotuner chooses parameters that are too aggressive then it will lead to this error. That's a normal part of autotuning as it tries to find the optimal values it may test some infeasible ones.

[dalyles]

I think I understand what you're saying, so this would require setting feasable ranges for the parameters to ensure that errors like this don't occur. Is that a correct way to understand this?

Thanks!

[rovinski]

I think it's more that some trials through the autotuner are expected to fail. It does not affect the integrity of the search. In fact, you likely want some trials to fail because if none fail, then your search space is likely limiting finding a more optimal solution.

[dalyles]

In my particular case, for each trial, the autotuner runs short of properly getting all the output results files done. This kind of failure is different from a failure such as getting timing violations for example.

[maliberty]

Not every failure will be a timing failure at the end of the run. If it tries to set the density too high the design will become unroutable. The only way it learns that is by trying it.