[USRP-users] Problems with "uhd::set_thread_priority_safe"
Marcus D. Leech
patchvonbraun at gmail.com
Wed Jul 1 15:37:23 EDT 2020
On 07/01/2020 02:40 PM, Nando Pellegrini wrote:
> sorry, i have to hold my horses.
> Let's forget all we said (or better i said) before , i have just done
> some more deep testing and actually UHD and its priority function have
> nothing to do with my problem.
> I had a suspect so made an application to write on a file the CPU
> speed and the run the B200 streaming loop and then a presto folding cycle.
> What is happening is the cpu speed which drops suddenly to the minimum
> (900Hz) and sometimes starts again to increase while sometime does
> not move anymore.
> I know that the cpu throttle is handled by Ubuntu and what came to my
> mind is that my cpu is not covered bu the current version of ubuntu18
> , if i start the B200 loop streaming at 40Mhz all goes ok with a CPU
> load (shown on the system monitor) with no threads over 10% so prone
> to believe that there is still a big margin before saturating the cpu.
> What sounds strange to me, when everything works at 40Mhz , is looking
> at system monitor a see no more then 5 threads running, one as i said
> at 10% while the others are very low but on the other side all the 8
> cpus are running at frequencies higher than 3Ghz in average monitored
> by running watch grep \"cpu MHz\" /proc/cpuinfo.
> Together with the frequency i have been monitoring also the cpu
> temperatures never going over 50° with fans at minimum speed.
> What seems to me is that there is a sort of trigger above which the
> activity is stopped and never recovered but far from the physical limits.
> The cpu on the laptop is an Intel 10th generation i7-10875H
> On W10 installed on the same PC with a dual boot and loading the cpu
> with a benchmark application and 16 threads running i can, see without
> time limitation, a continuous load close to 100% without overheating.
> At this point i will be happy if the problem is the cpu not covered by
> ubuntu so i'll stay at 40Mhz waiting for the right version.
> Apologies for what i said but was really not easy to think of such a
> problem. I tried to read the system log file but have no idea of what
> and where to look i could only see that the 8 cpus were correctly
> detected during the boot.
> One point of mine was still true, during my very first test of B200 on
> the new PC and before the latest Ubuntu updates i tried to run it to
> check if was affordable and since was able to run at 56Mhz and low cpu
> load for minutes (i cannot remember how many) i was very confident of
> the result, not it crashes in seconds.
> At this point any hints would be greatly appreciated.
What version of Ubuntu were you running on the new PC before upgrading
to 18.04? The libusb and kernel USB drivers have probably changed
since pre-18.04. Not sure.
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