Re: [Discuss-gnuradio] Expensive file write operation

[CEL]

Also note that a total of 40 MS/s, even at 16sc, is still 160 MB/s in
data; it's not guaranteed that a consumer SSD would sustain that rate
for arbitrarily long.
Average write rates these days most definitely suffice, but don't
underestimate the effect filesystem bookkeeping and imperfect buffer
handling on OS side.

Best regards,
Marcus

On Fri, 2019-08-30 at 19:56 +0200, sumit kumar wrote:
> Hi Nate, 
> Ok I understood your point. Thanks for the Freq hint :) , I missed that in 
> hurry.
> Regards
> Sumit 
> 
> On Fri, 30 Aug 2019 at 19:50, Nate Temple <address@hidden> wrote:
> > Hi Sumit, 
> > 
> > The change for the output type doesn't address the limits of the transport. 
> > The output change however does cut the rate of data you're storing to disk 
> > in half, which can be useful if you have longer recordings or if your SSD 
> > is the bottle neck.
> > 
> > This Akitio adapter box paired with a Mellanox card is a setup we have 
> > tested for TB3 to 10Gb:
> > 
> > https://www.newegg.com/akitio-model-t3pb-t3dis-aktu/p/N82E16814988001
> > https://store.mellanox.com/products/mellanox-mcx4121a-acat-connectx-4-lx-en-network-interface-card-25gbe-dual-port-sfp28-pcie3-0-x8-rohs-r6.html
> > 
> > I have not personally used this QNAP product, but others have reported it 
> > works fine (you'd want the one with the SFP port)
> > 
> > https://www.qnap.com/en-us/product/qna-tb-10gbe
> > 
> > 
> > One other observation on your flowgraph, you do not have the Ch1 Center 
> > Freq set correctly, it is currently set as 0.
> > 
> > 
> > Regards,
> > Nate Temple
> > 
> > 
> > On Fri, Aug 30, 2019 at 10:42 AM sumit kumar <address@hidden> wrote:
> > > Hi Nate, 
> > > Thanks. 
> > > My understanding about this was wrong :D I will order one adapter. 
> > > Meanwhile, I tried your suggestion, it is still giving overruns. 
> > > I have attached the screenshots of my config, can you please verify. 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > On Fri, 30 Aug 2019 at 19:12, Nate Temple <address@hidden> wrote:
> > > > Hi Sumit, 
> > > > 
> > > > Are you using a 1Gb transport to the X310?
> > > > 
> > > > The max data rate a 1Gb link can handle is ~25 MS/s @ sc16 OTW. With 
> > > > the two channels at 20 MS/s you're over this limit and would need to 
> > > > use 10Gb. If your laptop has a TB3/USB-C port, there are several TB3 to 
> > > > 10Gb adapters available.
> > > > 
> > > > 
> > > > Another observation -- if you switch the output type of the UHD Source 
> > > > block to be Complex int16 and then set your file sinks to have the data 
> > > > type Ints, you will cut the data rate in half that is being written to 
> > > > disk (complex 16bit Ints vs complex 32 bit floats). 
> > > > 
> > > > Regards,
> > > > Nate Temple
> > > > 
> > > > 
> > > > On Fri, Aug 30, 2019 at 9:59 AM sumit kumar <address@hidden> wrote:
> > > > > Hi, 
> > > > > I am trying to capture RF data thru X310 from 2 channels and writing 
> > > > > them to file using GNU Radio. But when I use a sampling rate of 20 
> > > > > MHz, packets start dropping badly. 
> > > > > 
> > > > > I have a very decent Laptop i7 8th Gen, SSD, 16 gb RAM. I also 
> > > > > observed the CPU performance, it does not look stressed at all. I 
> > > > > mean, none of the cores were reaching anywhere near to even 50%. 
> > > > > Am I doing something wrong? For 10MHz sampling rate it is good, no 
> > > > > overruns. 
> > > > > I have attached my flowgraph, and the cpu performance screenshot. 
> > > > > 
> > > > > 
> > > > > 
> > > > > 
> > > > > 
> > > > > 
> > > > > Regards
> > > > > -- 
> > > > > Sumit Kumar
> > > > > 
> > > > > 
> > > > > _______________________________________________
> > > > > Discuss-gnuradio mailing list
> > > > > address@hidden
> > > > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > > 
> > > 
> > > -- 
> > > Sumit Kumar
> > > 
> > > 
> 
> 
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
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