The-OpenROAD-Project
Global Routing is failing due to High Congetion for X-heep
Subject
[Stage]: Global Router.
Describe the bug
hello, Firstly my design is showing congestion too high .I have tried different values for placement density ,Halo but it gives same issue. how can i understand what to set .Can you kindly guide/suggest me.
export SYNTH_HIERARCHICAL = 1 export MAX_UNGROUP_SIZE = 100
export CORE_UTILIZATION = 20 export CORE_ASPECT_RATIO = 1 export CORE_MARGIN = 2
export PLACE_DENSITY_LB_ADDON = 0.2 export PLACE_DENSITY = 0.2
export RTLMP_FLOW = True
export MACRO_PLACE_HALO = 70 70 export MACRO_PLACE_CHANNEL = 140 140
Expected Behavior
It should keep Running
Environment
I dont find this file in my system i have just installed the ORFS from prebuilt libraries with latest release
(base) syed@syed-Latitude-E5450:~/OpenROAD-flow-scripts/flow$ which openroad
/usr/bin/openroad
(base) syed@syed-Latitude-E5450:/usr/bin$ openroad
OpenROAD 42ba30d730851a73bd2996c5673a05fd79520f87
Features included (+) or not (-): +Charts +GPU +GUI +Python : None
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.
openroad>
To Reproduce
https://drive.google.com/file/d/1KasNChJvnRrOwvnGMV3AjRBe5ORF0xrj/view?usp=sharing it is global route issue tar i am uploading but incase you need anything more please let me know
Relevant log output
OpenROAD 42ba30d730851a73bd2996c5673a05fd79520f87
Features included (+) or not (-): +Charts +GPU +GUI +Python : None
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 ORD-0030] Using 4 thread(s).
global_route -congestion_report_file ./reports/sky130hd/core_v_mini_mcu/base/congestion.rpt -congestion_iterations 30 -congestion_report_iter_step 5 -verbose
[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 = 0.4600 line-2-Via Pitch: 0.3400
[INFO GRT-0088] Layer met1 Track-Pitch = 0.3400 line-2-Via Pitch: 0.3400
[INFO GRT-0088] Layer met2 Track-Pitch = 0.4600 line-2-Via Pitch: 0.3500
[INFO GRT-0088] Layer met3 Track-Pitch = 0.6800 line-2-Via Pitch: 0.6150
[INFO GRT-0088] Layer met4 Track-Pitch = 0.9200 line-2-Via Pitch: 1.0400
[INFO GRT-0088] Layer met5 Track-Pitch = 3.4000 line-2-Via Pitch: 3.1100
[INFO GRT-0019] Found 33791 clock nets.
[INFO GRT-0001] Minimum degree: 2
[INFO GRT-0002] Maximum degree: 241
[INFO GRT-0003] Macros: 16
[INFO GRT-0043] No OR_DEFAULT vias defined.
[INFO GRT-0004] Blockages: 372462
[INFO GRT-0053] Routing resources analysis:
Routing Original Derated Resource
Layer Direction Resources Resources Reduction (%)
---------------------------------------------------------------
li1 Vertical 0 0 0.00%
met1 Horizontal 12970160 6355806 51.00%
met2 Vertical 9726815 6544551 32.72%
met3 Horizontal 6485080 4328358 33.26%
met4 Vertical 3892175 1940756 50.14%
met5 Horizontal 1296855 552162 57.42%
---------------------------------------------------------------
[INFO GRT-0101] Running extra iterations to remove overflow.
[INFO GRT-0197] Via related to pin nodes: 1722957
[INFO GRT-0198] Via related Steiner nodes: 54119
[INFO GRT-0199] Via filling finished.
[INFO GRT-0111] Final number of vias: 2325451
[INFO GRT-0112] Final usage 3D: 10350417
[INFO GRT-0096] Final congestion report:
Layer Resource Demand Usage (%) Max H / Max V / Total Overflow
---------------------------------------------------------------------------------------
li1 0 0 0.00% 0 / 0 / 0
met1 6355806 1206855 18.99% 0 / 0 / 0
met2 6544551 1350414 20.63% 0 / 0 / 0
met3 4328358 510560 11.80% 0 / 0 / 0
met4 1940756 267422 13.78% 0 / 0 / 0
met5 552162 38813 7.03% 0 / 0 / 0
---------------------------------------------------------------------------------------
Total 19721633 3374064 17.11% 0 / 0 / 0
[INFO GRT-0018] Total wirelength: 28806216 um
[INFO GRT-0014] Routed nets: 314920
Perform buffer insertion...
[INFO RSZ-0058] Using max wire length 2141um.
[ERROR GRT-0232] Routing congestion too high. Check the congestion heatmap in the GUI.
Error: global_route.tcl, 138 GRT-0232
Command exited with non-zero status 1
Elapsed time: 1:41:32[h:]min:sec. CPU time: user 5784.14 sys 305.97 (99%). Peak memory: 5691696KB.
Screenshots
No response
Additional Context
one thing to mention I have currently 8gb ram with which i have made 4 gb swap I will be ordering more 8gb to upgrade if the issue is due to it.
I think the congestion is the symptom. The problem starts in CTS with the insertion of many large buffers:
to fairly terrible effect:
@arthurjolo please investigate with help as needed from @precisionmoon
You can see the weird clumps of large buffers:
These clumps of buffers are caused by the level balancing of CTS. The level balancing is a week part of CTS and needs some enhencement, I am going to look into this.
@arthurjolo Do you need any more files ? export DESIGN_NICKNAME = core_v_mini_mcu export DESIGN_NAME = core_v_mini_mcu export PLATFORM = sky130hd
export VERILOG_FILES = ./designs/src/$(DESIGN_NICKNAME)/*.sv
export ADDITIONAL_LIBS = $(wildcard ./lib/.lib) export ADDITIONAL_GDSS = $(wildcard ./gds/.gds) export ADDITIONAL_LEFS = $(wildcard ./lef/*.lef) export SDC_FILE = ./designs/$(PLATFORM)/$(DESIGN_NICKNAME)/constraint.sdc
export ABC_AREA = 1
export SYNTH_HIERARCHICAL = 1 export MAX_UNGROUP_SIZE = 100
export CORE_UTILIZATION = 20 # increase to provide more space for buffer distribution.lower the core utilisation to provide more space for cell placement reducing dense clustering export CORE_ASPECT_RATIO = 1 export CORE_MARGIN = 2
export PLACE_DENSITY_LB_ADDON = 0.16 export PLACE_DENSITY = 0.16#lower the placement density to encourage a more even distribution of cells.
export RTLMP_FLOW = True
export MACRO_PLACE_HALO = 70 70 # Increase to provide more space around macros for better buffer placement export MACRO_PLACE_CHANNEL = 140 140 # Increasedto widen channels between macros
export FASTROUTE_TCL = $(PLATFORM_DIR)/fastroute.tcl
do these deduction is correct would these in any way improve it ?
These changes wouldn't prevent CTS from forming those clumps of buffers, the level balancing step is purposely forming them it is not a lack of space issue in this case.
I used the older version of ORFS and it worked to give the final GDS But Can I use Autotuner for this to find correct parameters?
The tool evolves over time so its not easy to say what's different. There is a CTS issue that needs fixing which will cause the results to change again. You are free to use the autotuner.
Hello i wanted to ask kindly is there any update for modifications in cts regarding the issue?
Hello i wanted to ask kindly is there any update for modifications in cts regarding the issue?
Hi, we are working on the solution for the CTS issue, the solution is to best arranged the level balancer buffer to avoid the clumps that are currently being generated. This fix it is still not ready, but as soon as it is it will be notified here.
@Wiki1998-dev The Pull Request with the CTS update was created. I tested the new version of CTS for your design and GRT is still having overflow, now the overflow is not related to any CTS nets or buffers. It seems that it is related to the high number of connections between the macros: