Isolcpus certainly does work. The best latencey I get it with 1,2,3 Sam
On Mon, Mar 29, 2021, 11:52 AM Gene Heskett <[email protected]> wrote: > On Monday 29 March 2021 10:46:54 Jon Elson wrote: > > > On 03/28/2021 09:46 PM, Gene Heskett wrote: > > > I, for comparison, I just built the latest git pull on my pi4, > > > getting these times, which I don't quite grok: > > > real 81m28.218s > > > user 133m40.185s > > > sys 30m24.466s > > > > > > How do I get user+sys at nearly 2x the real which is the same as the > > > actual wall time? > > > > Doesn't the Pi4 have multiple CPU cores? With 2 cores, > > total times can be 2X wall clock time. > > > > Jon > > The pi4 has 4 cores. /boot/cmdline.txt contains isolcpus=3, but I've > since read that isolcpus doesn't work on arms of any flavor. Not an > error in dmesg but supposedly ignored. Or is it? Running htop from > another login shell here, htop numbers them in base 1 format and core 4 > is never used, even when linuxcnc is running, so maybe it does work and > the uspace version doesn't use it? > > I'll take that out of /boot/cmdline.txt just for S&G. And now lcnc is > using cpu4 at nominally 23% while sitting idle. And does not appear to > be jumping around from the deadline scheduler activity. Interesting... > But "latency-test -period" is much worse. peaks at 60 some microseconds > very quckly. Put it back in, rebooted and now latency-test -period takes > 2 minutes to get past 10 microseconds. Strange but thats a kernel I > built too. > > However, htop is seeing it running? On a buster install on an old i5 > too!!! > > Crazy, so isocpus is indeed working on the arms, at least with my armhf > kernel. But that kernel install ain't easy. You can't "sudo make > install", you have to make a tarball containing the kernel /boot stuff > and its /lib stuffs which is about a 30 meg tarball, ship it to this > machine, and unpack it to the u-sd card, overwriting the /boot and /lib > contents already there. > > Theres a lot more to it than that doing it the first time though. Read > the README.txt in that directory. Goto the link in my sig, and extend > the address bar by adding lathe-stf/ which will then show you another > directory named linucnc4pi4b where the whole story resides in that > README > > And I forgot but I'd made another link, to the below address, add > buildbot-repo, gets you to the same dir. I'll update the lcnc files > there shortly. > > [ 0.601192] SMP: Total of 4 processors activated (432.00 BogoMIPS) > > Running linuxcnc at 900 mhz/core, it has plemty of time left. I've been > out on the net with firefox while lathe-pawn was running in a loop, no > problems with how lcnc was running while I was browsing the news sites. > > Thanks Jon > Cheers, Gene Heskett > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > _______________________________________________ > Emc-developers mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-developers > _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
