[Toybox] Interpreting top -H -O CPU output

[Dmitry Shmidt]

On Thu, Nov 14, 2019 at 8:32 AM enh <enh at google.com> wrote:

> On Wed, Feb 6, 2019 at 3:44 PM enh <enh at google.com> wrote:
> >
> > On Wed, Feb 6, 2019 at 2:34 PM Rob Landley <rob at landley.net> wrote:
> > >
> > > On 2/6/19 12:56 PM, Dmitry Shmidt wrote:
> > > > Hi Rob,
> > > >
> > > > I am using your top tool implementation for Android from
> > > > toybox project.
> > > > I am wondering if in the mode where it shows cpu usage
> > > > per thread, the total usage per task (process) is included in initial
> > > > ("main") thread?
> > >
> > > I don't really use threads much, Elliott provided most of the use
> cases for that.
> > >
> > > > For example: com.google.android.youtube.tv
> > > > <http://com.google.android.youtube.tv> shows 153% usage
> > > > for main thread and some more for other threads, like MainWebView -
> 31%.
> > > > Is this 31% included in 153% report or not?
> > >
> > > It should never report more than 100%, so it sounds like it is
> combining CPU
> > > usage from threads into the parent, yes.
> > >
> > > Hmmm... Top -H isn't showing TID by default,
> >
> > yeah, that seemed a bit weird to me, but it matches what the
> > traditional implementation did. (though threads aren't as common on
> > the desktop.)
> >
> > interestingly, i notice that our numbers don't add up. on the desktop,
> > total == running + sleeping, but our sleeping count is a lot lower
> > than it should be. (the desktop also says "Tasks:" or "Threads:"
> > depending on whether you supplied -H, and we don't.)
> >
> > we also don't do a good job of sizing the PID field on machines with a
> > large pid_max. this fixes both of those minor issues, but between the
> > removal of the `const` on the array and the floating point math i
> > assume you'll want to do this differently :-)
>
> any thoughts on how you'd like to fix this so i can send a patch you'd
> accept? (the bug bankruptcy bot is asking whether i'm actually going
> to do anything about this bug, which reminded me...)
>

I am ok with current solution. After we merged:
commit 168bfe5382c5a5034b7e208b3253f292b24999ec
Author: Rob Landley <rob at landley.net>
Date:   Sat Mar 2 22:05:00 2019 -0600

    Make top -H show TID instead of PID, not collate %CPU into parent thread
    (resulting in 400% CPU with 4 threads), and add a couple comments.

It works as we think it should.

> diff --git a/toys/posix/ps.c b/toys/posix/ps.c
> > index 079bdbd6..50f52b41 100644
> > --- a/toys/posix/ps.c
> > +++ b/toys/posix/ps.c
> > @@ -314,9 +314,9 @@ struct procpid {
> >  struct typography {
> >    char *name, *help;
> >    signed char width, slot;
> > -} static const typos[] = TAGGED_ARRAY(PS,
> > +} static /*const*/ typos[] = TAGGED_ARRAY(PS,
> >    // Numbers. (What's in slot[] is what's displayed, sorted
> numerically.)
> > -  {"PID", "Process ID", 5, SLOT_pid},
> > +  {"PID", "Process ID", 2, SLOT_pid},
> >    {"PPID", "Parent Process ID", 5, SLOT_ppid},
> >    {"PRI", "Priority (dynamic 0 to 139)", 3, SLOT_priority},
> >    {"NI", "Niceness (static 19 to -20)", 3, SLOT_nice},
> > @@ -1262,6 +1262,16 @@ static void default_ko(char *s, void *fields,
> char *err,
> > struct arg_list *arg)
> >    if (x) help_help();
> >  }
> >
> > +static void init_pid_width(void)
> > +{
> > +  FILE *fp = xfopen("/proc/sys/kernel/pid_max", "re");
> > +  int pid_max;
> > +
> > +  fscanf(fp, "%d", &pid_max);
> > +  fclose(fp);
> > +  typos[0].width = ceil(log10(pid_max));
> > +}
> > +
> >  void ps_main(void)
> >  {
> >    char **arg;
> > @@ -1270,6 +1280,7 @@ void ps_main(void)
> >    int i;
> >
> >    TT.ticks = sysconf(_SC_CLK_TCK); // units for starttime/uptime
> > +  init_pid_width();
> >
> >    if (-1 != (i = tty_fd())) {
> >      struct stat st;
> > @@ -1546,8 +1557,9 @@ static void top_common(
> >            for (i = 0; i<mix.count; i++)
> >              run[1+stridx("RSTZ", *string_field(mix.tb[i], &field))]++;
> >            sprintf(toybuf,
> > -            "Tasks: %d total,%4ld running,%4ld sleeping,%4ld stopped,"
> > -            "%4ld zombie", mix.count, run[1], run[2], run[3], run[4]);
> > +            "%ss: %d total, %3ld running, %3ld sleeping, %3ld stopped, "
> > +            "%3ld zombie", FLAG(H)?"Thread":"Task", mix.count,
> > +            run[1], run[2], run[3], run[4]);
> >            lines = header_line(lines, 0);
> >
> >            if (readfile("/proc/meminfo", toybuf, sizeof(toybuf))) {
> > @@ -1697,6 +1709,7 @@ static void top_setup(char *defo, char *defk)
> >  {
> >    TT.ticks = sysconf(_SC_CLK_TCK); // units for starttime/uptime
> >    TT.tty = tty_fd() != -1;
> > +  init_pid_width();
> >
> >    // Are we doing "batch" output or interactive?
> >    if (FLAG(b)) TT.width = TT.height = 99999;
> >
> >
> > > and top -H -O TID is never showing
> > > more than one instance of the same PID... until I sort by TID, and
> then I get a
> > > bunch of chrome threads under the same PID, each with 1.5% of the CPU.
> So yeah,
> > > CPU usage is per process here, not per thread.
> > >
> > > I'm trying to cut a release, but let me add that to the todo list for
> next
> > > release. (I should try to come up with a better test case because y
> system's way
> > > too loaded normally...)
> > >
> > > Rob
> > > _______________________________________________
> > > Toybox mailing list
> > > Toybox at lists.landley.net
> > > http://lists.landley.net/listinfo.cgi/toybox-landley.net
>
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