Raspberry Pi 4 and bad latency.. SOLUTIONS?
- hitchhiker
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						22 Mar 2025 13:34				#324548
		by hitchhiker
	
	
		
			
	
	
		
			
			 		
													
	
				Raspberry Pi 4 and bad latency.. SOLUTIONS? was created by hitchhiker			
			
				Hi guys!I am on a new Project and found a mesa 7c81 an 7i92 on the flewmarket... dont know why someone sell it on a flewmarket...i start reading about the 7c81 and look to my boxes and found a raspberry pi 4 b version with 8gb ram.. oki load the image for the sd card from the linuxcnc website and bring it up.i isolate cpu 1 2 3 but latency doesnt go down.
Any tips?
in the config i disable audio blueetooth and overclock to 6v and 2000mhz..
which information i can share to get the cow frome the ice?
thanks all
 
 
 
			
					Any tips?
in the config i disable audio blueetooth and overclock to 6v and 2000mhz..
which information i can share to get the cow frome the ice?
thanks all
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- tommylight
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						22 Mar 2025 13:56				#324552
		by tommylight
	
	
		
			
	
			
			 		
													
	
				Replied by tommylight on topic Raspberry Pi 4 and bad latency.. SOLUTIONS?			
			
				try this			
					latency-histogram --nobase --sbinsize 1000 --showPlease Log in or Create an account to join the conversation.
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						22 Mar 2025 13:59				#324553
		by hitchhiker
	
	
		
			
	
			
			 		
													
	
				Replied by hitchhiker on topic Raspberry Pi 4 and bad latency.. SOLUTIONS?			
			
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						22 Mar 2025 14:25				#324554
		by hitchhiker
	
	
		
			
	
	
		
			
			 		
													
	
				Replied by hitchhiker on topic Raspberry Pi 4 and bad latency.. SOLUTIONS?			
			
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						22 Mar 2025 16:52				#324564
		by tommylight
	
	
		
			
	
			
			 		
													
	
				Replied by tommylight on topic Raspberry Pi 4 and bad latency.. SOLUTIONS?			
			
				Much better, move on to wiring and making chips!
Keep an eye when starting LinuxCNC if it complains about latency, it shows a warning usually when enabling it or later during use.
					Keep an eye when starting LinuxCNC if it complains about latency, it shows a warning usually when enabling it or later during use.
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						22 Mar 2025 21:25				#324586
		by rodw
	
	
		
			
	
			
			 		
													
	
				Replied by rodw on topic Raspberry Pi 4 and bad latency.. SOLUTIONS?			
			
				Your latency is a pass, move on			
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						23 Mar 2025 06:35				#324628
		by hitchhiker
	
	
		
			
	
			
			 		
													
	
				Replied by hitchhiker on topic Raspberry Pi 4 and bad latency.. SOLUTIONS?			
			
				on ny m73 i have a jitter of 1000... so what is the reason thst you say that this latency is good???? thanks			
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						23 Mar 2025 07:27				#324630
		by rodw
	
	
		
			
	
			
			 		
													
	
				Replied by rodw on topic Raspberry Pi 4 and bad latency.. SOLUTIONS?			
			
				Assuming you use the 7c81's FGPA for stepgen and don't sofware step, you don't need a base thread so latency requirements is much relaxed. I'd be happy with anything under 130,000 with 200,000 at a pinch			
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						23 Mar 2025 07:47				#324633
		by hitchhiker
	
	
		
			
	
			
			 		
													
	
				Replied by hitchhiker on topic Raspberry Pi 4 and bad latency.. SOLUTIONS?			
			
				or a 7i92... i payed for both cards 100 euros...
so for my information... on a normal pc like optiplex 3020m or lenovo m73 tiny.. i have latency under 2000... but i never looked this way in the histogram.
can you explain me the spike?! please
					so for my information... on a normal pc like optiplex 3020m or lenovo m73 tiny.. i have latency under 2000... but i never looked this way in the histogram.
can you explain me the spike?! please
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						23 Mar 2025 07:52		 -  23 Mar 2025 07:53		#324634
		by Aciera
	
	
		
			
				
Note the missing spikes (colored in blue/red) at the extreme left and right of the graph.
					
	
	
			 		
													
	
				Replied by Aciera on topic Raspberry Pi 4 and bad latency.. SOLUTIONS?			
			same values or i am wrong??
Note the missing spikes (colored in blue/red) at the extreme left and right of the graph.
		Last edit: 23 Mar 2025 07:53  by Aciera.			
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