[Bug 232153] Processes without explicit cpuset only use half the SMP threads (on a Ryzen)

[bugzilla-noreply at freebsd.org]

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=232153

Eric van Gyzen <vangyzen at FreeBSD.org> changed:

           What    |Removed                     |Added
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                 CC|                            |vangyzen at FreeBSD.org

--- Comment #1 from Eric van Gyzen <vangyzen at FreeBSD.org> ---
I'm not seeing this behavior on my Ryzen 7 2700X running r339207 (77 commits
beyond 12.0-ALPHA8).

I ran this to get constant high load:

make -C /usr/src/lib/clang/libllvm -j16

I see all 16 CPU threads getting scheduled:

last pid: 78555;  load averages: 16.45, 14.08,  8.70    up 1+15:21:55  12:32:09
155 processes: 18 running, 137 sleeping
CPU 0:  95.3% user,  0.0% nice,  4.7% system,  0.0% interrupt,  0.0% idle
CPU 1:  98.8% user,  0.0% nice,  1.2% system,  0.0% interrupt,  0.0% idle
CPU 2:  94.5% user,  0.0% nice,  4.7% system,  0.8% interrupt,  0.0% idle
CPU 3:  98.0% user,  0.0% nice,  2.0% system,  0.0% interrupt,  0.0% idle
CPU 4:  96.1% user,  0.0% nice,  3.9% system,  0.0% interrupt,  0.0% idle
CPU 5:  98.8% user,  0.0% nice,  1.2% system,  0.0% interrupt,  0.0% idle
CPU 6:  98.0% user,  0.0% nice,  2.0% system,  0.0% interrupt,  0.0% idle
CPU 7:  94.1% user,  0.0% nice,  5.9% system,  0.0% interrupt,  0.0% idle
CPU 8:  96.9% user,  0.0% nice,  3.1% system,  0.0% interrupt,  0.0% idle
CPU 9:  97.6% user,  0.0% nice,  2.4% system,  0.0% interrupt,  0.0% idle
CPU 10: 96.1% user,  0.0% nice,  3.5% system,  0.4% interrupt,  0.0% idle
CPU 11: 97.2% user,  0.0% nice,  2.8% system,  0.0% interrupt,  0.0% idle
CPU 12: 93.3% user,  0.0% nice,  6.7% system,  0.0% interrupt,  0.0% idle
CPU 13: 98.8% user,  0.0% nice,  1.2% system,  0.0% interrupt,  0.0% idle
CPU 14: 96.9% user,  0.0% nice,  2.0% system,  1.2% interrupt,  0.0% idle
CPU 15: 98.0% user,  0.0% nice,  2.0% system,  0.0% interrupt,  0.0% idle
Mem: 3296M Active, 6227M Inact, 109M Laundry, 20G Wired, 1202M Free
ARC: 15G Total, 8637M MFU, 4731M MRU, 676K Anon, 603M Header, 1344M Other
     12G Compressed, 19G Uncompressed, 1.57:1 Ratio
Swap: 8192M Total, 8192M Free

  PID USERNAME    THR PRI NICE   SIZE    RES STATE    C   TIME    WCPU COMMAND
78537 vangyzen      1  87    0   232M   207M CPU2     2   0:07  99.81% c++
78546 vangyzen      1  86    0   214M   189M CPU8     8   0:06  99.66% c++
78467 vangyzen      1  95    0   252M   228M CPU5     5   0:13  99.61% c++
78552 vangyzen      1  84    0   195M   170M RUN     10   0:05  99.11% c++
78474 vangyzen      1  94    0   229M   204M CPU1     1   0:12  98.53% c++
78549 vangyzen      1  85    0   211M   186M CPU9     9   0:06  98.34% c++
78528 vangyzen      1  88    0   238M   214M CPU3     3   0:07  98.34% c++
78531 vangyzen      1  87    0   234M   210M CPU15   15   0:07  97.68% c++
78543 vangyzen      1  86    0   216M   191M CPU13   13   0:06  97.66% c++
78519 vangyzen      1  89    0   265M   240M CPU12   12   0:08  97.49% c++
78498 vangyzen      1  91    0   254M   229M CPU11   11   0:10  97.25% c++
78522 vangyzen      1  89    0   256M   232M CPU14   14   0:08  97.22% c++
78540 vangyzen      1  86    0   218M   193M CPU6     6   0:06  97.05% c++
78525 vangyzen      1  88    0   235M   210M CPU4     4   0:07  96.88% c++
78534 vangyzen      1  87    0   233M   209M CPU0     0   0:07  93.82% c++
78555 vangyzen      1  83    0   188M   163M CPU7     7   0:04  92.36% c++

I did not explicitly set a cpuset.

Maybe try updating?  I imagine the ALPHA9 builds are running now.

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