Re: Periodic rant about SCHED_ULE
- Reply: Mark Millard : "Re: Periodic rant about SCHED_ULE"
- In reply to: Mark Millard : "Re: Periodic rant about SCHED_ULE"
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Date: Thu, 23 Mar 2023 02:44:19 UTC
On Mar 22, 2023, at 18:08, Mark Millard <marklmi@yahoo.com> wrote: > On Mar 22, 2023, at 18:03, Mark Millard <marklmi@yahoo.com> wrote: > >> On Mar 22, 2023, at 16:17, Mark Millard <marklmi@yahoo.com> wrote: >> >>> On Mar 22, 2023, at 15:39, Mark Millard <marklmi@yahoo.com> wrote: >>> >>>> On Mar 22, 2023, at 13:34, Mark Millard <marklmi@yahoo.com> wrote: >>>> >>>>> On Mar 22, 2023, at 12:40, George Mitchell <george+freebsd@m5p.com> wrote: >>>>> >>>>>> On 3/22/23 15:21, Mark Millard wrote: >>>>>>> George Mitchell <george+freebsd@m5p.com> wrote on >>>>>>> Date: Wed, 22 Mar 2023 17:36:39 UTC : >>>>>>> [...] >>>>>>>> Here are the very complicated instructions for reproducing the problem: >>>>>>>> 1. Install and start misc/dnetc from ports. >>>>>>> Installing is likely easy, as likely would be building >>>>>>> with default options (if any). I know nothing about >>>>>>> starting misc/dnetc so that is research. (Possibly >>>>>>> trivial, although if it has alternatives to control >>>>>>> then I'd need to match that context too.) >>>>>> >>>>>> service dnetc start >>>>> >>>>> I built and installed misc/dnetc and got a binary >>>>> blob that clearly was not built in my environment: >>>>> >>>>> # file /usr/local/distributed.net/dnetc >>>>> /usr/local/distributed.net/dnetc: ELF 64-bit LSB executable, x86-64, version 1 (FreeBSD), statically linked, for FreeBSD 10.1 (1001515), FreeBSD-style, stripped >>>>> >>>>> Way older FreeBSD vintage than the locally available toolchains >>>>> would normally build. Some might be cautious about such a thing. >>>>> >>>>> The man page reported that: >>>>> >>>>> QUOTE >>>>> If you have never run the client before, it will initiate the menu-driven >>>>> configuration. Save and quit when done, the configuration file will be >>>>> saved in the same directory as the client. Now, simply restart the >>>>> client. From that point on it will use the saved configuration. >>>>> END QUOTE >>>>> >>>>> I've not seen what the configuration asks about yet. >>>> >>>> I went through the configuration, basically just looking >>>> at it, other than providing an E-mail address. Then . . . >>>> >>>> $ sudo service dnetc start >>>> Password: >>>> Cannot 'start' dnetc. Set dnetc_enable to YES in /etc/rc.conf or use 'onestart' instead of 'start'. >>>> >>>> $ sudo service dnetc onestart >>>> >>>> I just let it run without any extra competing activity, other >>>> than I had my patched version of top running. It records and >>>> reports various maximum-observed (MaxObs) figures, here >>>> the load averages being relevant. >>>> >>>> Top showed that dnetc started 32 processes, one per hardware >>>> thread. Mostly I saw: 100% nice and 0% idle. >>>> >>>> Letting it run and then looking at the load averages (and >>>> their matching MaxObs figures) after something like 60+ min >>>> (not carefully timed: was doing other things) showed: >>>> >>>> load averages: 31.97, 31.88, 31.66 MaxObs: 32.12, 31.97, 31.66 >>>> >>>> (Note: The machine had been up for over 2.75 days before >>>> starting this and had not been building much of anything >>>> during that time.) >>>> >>>> I've not yet experimented with having other, significant >>>> competing activity. >>>> >>>>>>>> 2. Run "make buildworld". >>>>>>> So on the 32 hardware-thread (16 cores) amd64 machine that >>>>>>> I have access to, the test is to only have buildworld use >>>>>>> about one hardware thread, no matter what else is going on. >>>>>>> I never would have guessed that the steps would not involve >>>>>>> more like -j$(sysctl -n hw.ncpu) (so around -j32 in this >>>>>>> context). So it is good that you provided your note or >>>>>>> I'd not know if I'd done similarly or not when trying such. >>>>>>> [Note: -j1 and lack of -j are not strictly equivalent in >>>>>>> how make operates. As I remember, the distinction makes >>>>>>> a notable difference in the number of subprocesses created >>>>>>> directly by make (one per action "line" vs. one for the >>>>>>> whole block?). So even using -j1 might make a difference >>>>>>> vs. what you specified. I'd have to test to see.] >>>>>> >>>>>> I am literally running "make buildworld" with no additional options. >>>>> >>>>> So required for repeating your results, but likely making >>>>> such results not be interesting relative to how I normally >>>>> deal with buildworld buildkernel and the likel, no matter >>>>> if there is other activity in an overlapping time frame or >>>>> not: my time preferences are too strong to wait for a single >>>>> hardware thread to do my normal builds, even with no >>>>> competing activity on the builder. >>>>> >>>>>>>> Standard out conveniently reports how long it took (wall clock). >>>>>>> But nothing in your instructions indicate about how >>>>>>> to get an idea much progress dnetc made during the >>>>>>> various tests? [...] >>>>>> >>>>>> Honestly, I've never worried about this part. But dnetc logs its >>>>>> progress in /usr/local/distributed.net/dnetc.txt, though not in terms >>>>>> that are easy to relate to real-world progress. Oddly, when I run >>>>>> "make buildworld," I'm primarily interested in getting the world built. >>>>>> Perhaps others feel differently. >>>>> >>>>> Off topic for the specifics of the actual benchmark >>>>> that you run: >>>>> >>>>> Then why not use of -jN ? In my context, any buildworld >>>>> using -j1 or no -j at all takes a huge amount of time >>>>> longer than letting it use all the hardware threads (or >>>>> so). (I've avoided having any I/O bound contexts for >>>>> such.) It does not take additional load on the system >>>>> for that to be true --including on the 4-core small arm >>>>> boards when I happen to buildworld on such (rare). >>>>> >>>>> >>>>>>> [...] >>>>>>> FYI: I've never built with and run the alternate >>>>>>> scheduler so if there is any appropriate background >>>>>>> for that that would not be obvious on finding basic >>>>>>> instructions, it would be appropriate to provide >>>>>>> such notes. >>>>>>> [...] >>>>>> >>>>>> You have to build a new kernel, using a config file in which you have >>>>>> replaced "options SCHED_ULE" with "options SCHED_4BSD". -- George >>>>> >>>>> Thanks for the notes. >>>>> >>>>> I've not decided if I'll do anything with the binary >>>>> blob or not. >>>> >>> >>> FYI: >>> >>> It is not your specific experiment, but I started my >>> "extra load" experimenst with . . . >>> >>> I started a -j32 buildworld buildkernel with dnetc still >>> running. I'm generally seeing around 55% Active and 42% >> >> Note "Active": user, sorry. >> >>> nice, < 2% system (it was building libllvm at this point). >>> At that time: >>> >>> load averages: 64.41, 60.52, 49.81 MaxObs: 64.47, 60.52, 49.81 >>> >> >> Contrasting results for some obj-lib32 build activity: >> much more variety of User, nice, and system, including >> times with < 5% user, 90+% nice. But not typical overall. >> But lots of time roughly around 50%/50% or 35%/60%. There >> were times with 15+% system. >> >> Somewhat after buildkernel started: >> >> load averages: 69.15, 64.12, 58.72 MaxObs: 75.98, 64.12, 58.72 >> >> Harder to summarize, so overall timing reports from the >> buildworld and buildkernel stages. >> >> >> buildworld: >> >> -------------------------------------------------------------- >> ... World build completed on Wed Mar 22 16:37:57 PDT 2023 >> ... World built in 2615 seconds, ncpu: 32, make -j32 >> -------------------------------------------------------------- >> >> >> buildkernel: >> >> -------------------------------------------------------------- >> ... Kernel build for GENERIC-NODBG completed on Wed Mar 22 16:43:10 PDT 2023 >> -------------------------------------------------------------- >> ... Kernel(s) GENERIC-NODBG built in 311 seconds, ncpu: 32, make -j32 >> -------------------------------------------------------------- >> >> Afterwards: >> >> load averages: 36.08, 53.14, 55.79 MaxObs: 75.98, 65.77, 59.84 >> >> >> I then did (not all in the same window): >> >> $ sudo service dnetc onestop >> # rm -fr /usr/obj/BUILDs/main-amd64-nodbg-clang-alt/usr/ >> >> before another -j32 buildworld buildkernel (no dnetc). The >> reuslts for this were: >> >> >> buildworld: >> >> -------------------------------------------------------------- >> ... World build completed on Wed Mar 22 17:39:19 PDT 2023 >> ... World built in 1240 seconds, ncpu: 32, make -j32 >> -------------------------------------------------------------- >> >> (compared to the 2615 for dnetc also in use) >> >> >> buildkernel: >> >> -------------------------------------------------------------- >> ... Kernel build for GENERIC-NODBG completed on Wed Mar 22 17:41:17 PDT 2023 >> -------------------------------------------------------------- >> ... Kernel(s) GENERIC-NODBG built in 118 seconds, ncpu: 32, make -j32 >> -------------------------------------------------------------- >> >> (compared to the 311 for dnetc also in use) > > I forgot to show the MaxObs load averages for the no-dnetc > context: > > MaxObs: 39.77, 32.15, 25.75 > >> Experiments without -j32 will take a lot longer, even >> without dnetc in use. I'm not sure there will be such >> results today. >> > I decided to do some more of the less time consuming testing. SCHED_4BSD, no dnetc, -j32 buildworld buildkernel : buildworld: -------------------------------------------------------------- ... World build completed on Wed Mar 22 19:16:35 PDT 2023 ... World built in 1235 seconds, ncpu: 32, make -j32 -------------------------------------------------------------- (compared to 1240 for SCHED_ULE) So: no significant difference. buildkernel (SCHED_4BSD building a SCHED_4BSD): -------------------------------------------------------------- ... Kernel build for GENERIC-NODBG-SCHED_4BSD completed on Wed Mar 22 19:18:34 PDT 2023 -------------------------------------------------------------- ... Kernel(s) GENERIC-NODBG-SCHED_4BSD built in 119 seconds, ncpu: 32, make -j32 -------------------------------------------------------------- (compared to 118 for SCHED_ULE building a SCHED_ULE) So: no significant difference. I'll try it with dnetc also active. === Mark Millard marklmi at yahoo.com