Re: Arm v7 RPi2 -current unresponsive to debugger escape during buildworld

On Mon, Nov 24, 2025 at 07:40:21PM -0800, Mark Millard wrote:
> On Nov 24, 2025, at 18:07, bob prohaska <fbsd@www.zefox.net> wrote:
> 
> > A few minutes ago a Pi2 running buildworld for -current locked up again, with no
> > responsie to the debugger escape.
> > 
> > The system was swapping fairly hard but not stuck, maybe 600 MB in use, eventually
> > swap use declined but in minutes it got stuck with top displaying:
> > 
> > last pid: 51520;  load averages:    2.82,    2.96,    2.96                     up 1+02:48:27  16:27:58
> > 57 processes:  3 running, 54 sleeping
> > CPU: 66.4% user,  0.0% nice, 16.0% system,  0.3% interrupt, 17.4% idle
> > Mem: 183M Active, 540M Inact, 416K Laundry, 175M Wired, 98M Buf, 19M Free
> > Swap: 2048M Total, 23M Used, 2025M Free, 1% Inuse
> > 
> >  PID USERNAME    THR PRI NICE   SIZE    RES STATE    C   TIME    WCPU COMMAND
> > 51497 root          5  59    0   352M   208M uwait    3   0:08 161.51% ld.lld
> > 51518 root          1 101    0   167M    71M CPU1     1   0:03  87.52% cc
> > 51520 root          1  59    0   167M    72M RUN      2   0:03  67.88% cc
> > 11811 root          1   0    0  6724K  1456K CPU0     0   5:51   0.46% top
> > 2047 root          1   0    0  4676K   704K select   0   1:08   0.09% powerd
> > 2206 bob           1   0    0    14M  1212K select   0   0:46   0.06% sshd-session
> > 2119 root          1   9    0    14M  2320K select   1   1:27   0.00% sshd
> > 
> > The over-100% utilization for cpu 3 looks somewhat implausible.
> 
> It is very plausible based on the above: note that THR
> (thread count) indicates 5 for ld.lld : It can have more
> than one core in use at the same time part of the time
> in order to have 161.51% WCPU. More than core 3 was in
> use by ld.lld . Some of the information shown is likely
> specific to the main/original thread.
> 
> (Top has a display mode that shows one thread per line
> instead of one process per line. It can also display
> Thread IDs instead of Process IDs. But PID can sometimes
> make it easier to identify which threads are part of one
> process. Non-thread-specific information is replicated.
> Top can also display more of the command line text.)

I completely misunderstood the meaning of "raw" vs "weighted"
CPU. Apparently the "raw" value reflects how much more work 
the CPU _could_ be doing, at least in terms of time. 

Thanks for the clarification!

bob prohaska