Re: [USRP-users] DMA FIFO latency with X310

Dear lord. The calculator on my iPhone only goes to 1e8 in portrait mode. I had not noticed, so I slipped a decimal place. Doh!! Sent from my iPhone > On Dec 30, 2020, at 11:48 AM, EJ Kreinar wrote: > >  > Simple math is not working out for me today-- Maybe it's the holidays?? > > I think a

Re: [USRP-users] DMA FIFO latency with X310

Simple math is not working out for me today-- Maybe it's the holidays?? I think a 9000 *byte* packet would be 9000*8/1e9 = 72 microseconds ... However the FFT input needs 8192 *samples* which is 8192*4*8/1e9 = 262 microseconds! Seems like your latency is driven by sending data over the network h

Re: [USRP-users] DMA FIFO latency with X310

Simple math. A 9000 *byte* packet is 72000 *bits* At 1.0e9 *bits/sec* that’s a latency of 720usec Sent from my iPhone > On Dec 30, 2020, at 8:55 AM, Jorge Arroyo Giganto via USRP-users > wrote: > >  > Hi EJ, > > Yes, I tried replacing the DMA FIFO with a normal FIFO and the latency got

Re: [USRP-users] DMA FIFO latency with X310

Hi EJ, Yes, I tried replacing the DMA FIFO with a normal FIFO and the latency got a bit worse and more irregular (I'm guessing that's due to not smoothing that burstiness in the Ethernet interface with the DMA FIFO you mentioned). I have just tried your graph suggestion (Host -> FFT -> FIFO -> Ho

Re: [USRP-users] DMA FIFO latency with X310

Can you replace the DMA FIFO with a normal FIFO? The DMA FIFO is mostly used for continuous streaming-- it provides a data buffer using off-chip DRAM that smooths out any burstiness in the ethernet interface so there's no overflows/underruns-- but it should not be needed for your application. You

Re: [USRP-users] DMA FIFO latency with X310

Hi Nick, I am running the X310 interface at 1Gbit using the SFP Adapter that came with the X310. At first I fowollowed the advice from Ettus USRP Manual of setting the MTU to 1500 and _frame_size=1472 when runni