Date: Wed, 22 Mar 2023 18:08:54 -0700 From: Mark Millard <marklmi@yahoo.com> To: George Mitchell <george+freebsd@m5p.com> Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Re: Periodic rant about SCHED_ULE Message-ID: <0196A767-5DC2-4DA3-BA5E-62A358CBCF64@yahoo.com> In-Reply-To: <E30D9325-60C4-42A8-9929-5F51F8F102E0@yahoo.com> References: <6BD317F2-7EDD-45C0-9DC9-5B94C1BBB8E1.ref@yahoo.com> <6BD317F2-7EDD-45C0-9DC9-5B94C1BBB8E1@yahoo.com> <952d9795-19dc-8ad1-bb75-5c556ca6795a@m5p.com> <E8A93C10-F5A4-4473-9AED-299C108CAD6C@yahoo.com> <78EF511D-BAF1-495F-BAC9-03AC1B8FD56A@yahoo.com> <A0F19E2A-A63E-4CBD-B962-CEEC455BBC0A@yahoo.com> <E30D9325-60C4-42A8-9929-5F51F8F102E0@yahoo.com>
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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: >=20 >> On Mar 22, 2023, at 15:39, Mark Millard <marklmi@yahoo.com> wrote: >>=20 >>> On Mar 22, 2023, at 13:34, Mark Millard <marklmi@yahoo.com> wrote: >>>=20 >>>> On Mar 22, 2023, at 12:40, George Mitchell <george+freebsd@m5p.com> = wrote: >>>>=20 >>>>> 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.) >>>>>=20 >>>>> service dnetc start >>>>=20 >>>> I built and installed misc/dnetc and got a binary >>>> blob that clearly was not built in my environment: >>>>=20 >>>> # 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 >>>>=20 >>>> Way older FreeBSD vintage than the locally available toolchains >>>> would normally build. Some might be cautious about such a thing. >>>>=20 >>>> The man page reported that: >>>>=20 >>>> 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. =46rom that point on it will use the saved configuration. >>>> END QUOTE >>>>=20 >>>> I've not seen what the configuration asks about yet. >>>=20 >>> I went through the configuration, basically just looking >>> at it, other than providing an E-mail address. Then . . . >>>=20 >>> $ sudo service dnetc start >>> Password: >>> Cannot 'start' dnetc. Set dnetc_enable to YES in /etc/rc.conf or use = 'onestart' instead of 'start'. >>>=20 >>> $ sudo service dnetc onestart >>>=20 >>> 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. >>>=20 >>> Top showed that dnetc started 32 processes, one per hardware >>> thread. Mostly I saw: 100% nice and 0% idle. >>>=20 >>> 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: >>>=20 >>> load averages: 31.97, 31.88, 31.66 MaxObs: 32.12, 31.97, 31.66 >>>=20 >>> (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.) >>>=20 >>> I've not yet experimented with having other, significant >>> competing activity. >>>=20 >>>>>>> 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.] >>>>>=20 >>>>> I am literally running "make buildworld" with no additional = options. >>>>=20 >>>> 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. >>>>=20 >>>>>>> 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? [...] >>>>>=20 >>>>> 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. >>>>=20 >>>> Off topic for the specifics of the actual benchmark >>>> that you run: >>>>=20 >>>> 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). >>>>=20 >>>>=20 >>>>>> [...] >>>>>> 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. >>>>>> [...] >>>>>=20 >>>>> You have to build a new kernel, using a config file in which you = have >>>>> replaced "options SCHED_ULE" with "options SCHED_4BSD". -- = George >>>>=20 >>>> Thanks for the notes. >>>>=20 >>>> I've not decided if I'll do anything with the binary >>>> blob or not. >>>=20 >>=20 >> FYI: >>=20 >> It is not your specific experiment, but I started my >> "extra load" experimenst with . . . >>=20 >> I started a -j32 buildworld buildkernel with dnetc still >> running. I'm generally seeing around 55% Active and 42% >=20 > Note "Active": user, sorry. >=20 >> nice, < 2% system (it was building libllvm at this point). >> At that time: >>=20 >> load averages: 64.41, 60.52, 49.81 MaxObs: 64.47, 60.52, 49.81 >>=20 >=20 > 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. >=20 > Somewhat after buildkernel started: >=20 > load averages: 69.15, 64.12, 58.72 MaxObs: 75.98, 64.12, 58.72 >=20 > Harder to summarize, so overall timing reports from the > buildworld and buildkernel stages. >=20 >=20 > buildworld: >=20 > -------------------------------------------------------------- > ... World build completed on Wed Mar 22 16:37:57 PDT 2023 > ... World built in 2615 seconds, ncpu: 32, make -j32 > -------------------------------------------------------------- >=20 >=20 > buildkernel: >=20 > -------------------------------------------------------------- > ... 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 > -------------------------------------------------------------- >=20 > Afterwards: >=20 > load averages: 36.08, 53.14, 55.79 MaxObs: 75.98, 65.77, 59.84 >=20 >=20 > I then did (not all in the same window): >=20 > $ sudo service dnetc onestop > # rm -fr /usr/obj/BUILDs/main-amd64-nodbg-clang-alt/usr/ >=20 > before another -j32 buildworld buildkernel (no dnetc). The > reuslts for this were: >=20 >=20 > buildworld: >=20 > -------------------------------------------------------------- > ... World build completed on Wed Mar 22 17:39:19 PDT 2023 > ... World built in 1240 seconds, ncpu: 32, make -j32 > -------------------------------------------------------------- >=20 > (compared to the 2615 for dnetc also in use) >=20 >=20 > buildkernel: >=20 > -------------------------------------------------------------- > ... 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 > -------------------------------------------------------------- >=20 > (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. >=20 =3D=3D=3D Mark Millard marklmi at yahoo.com =3D=3D=3D Mark Millard marklmi at yahoo.com
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