[Crash-utility] [PATCH RFC 0/1] Display relative lag of each CPU

[Dave Anderson]

----- Original Message -----
> Hi, Dave.
> 
> The question about indentation for column output is whether you prefer
> simple tabulation ("\t"), or calculated amount of spaces. Tabs are
> simpler, but in case we have big CPU number, output may be shifted.

Tabs aren't used in any crash command output, so preferably it would use
a calculated number of leading spaces, typically a minimum of 2 shifted
right depending upon the number of cpus, so that the colons line up:

   CPU 9:
  CPU 10:

Thanks,
  Dave

> 
> This is the only concern from me regarding this submission.
> 
> On Wed, Nov 8, 2017 at 5:33 PM, Dave Anderson <anderson at redhat.com> wrote:
> >
> >
> > ----- Original Message -----
> >> While analyzing vmcore it is useful to have an information
> >> about relative lag of each CPU. Usually, people do something like this:
> >>
> >> runq -t | grep CPU | sort -k3r |
> >>   awk 'NR==1{now=strtonum("0x"$3)}1{printf"%s\t%7.2fs behind\n",
> >>        $0,(now-strtonum("0x"$3))/1000000000}'
> >>
> >> Here, most recent runqueue timestamp is taken as a basis, and other
> >> runqueues are assumed to lag behind it. This information can tell
> >> the reviewer which CPU is experiencing some lockup, which is
> >> especially useful for vmcores taken in virtual machines.
> >>
> >> I think it would be nice to have this feature implemented by crash
> >> utility itself.
> >
> > OK...
> >
> >> Since this is an RFC and if this enhancement looks useful, I'd like
> >> to ask to assist me with output indentation since dump_on_rq_timestamp(),
> >> for instance, looks too implicit and (honestly) awful to use as it is.
> >
> > I don't know what you need assistance for?
> >
> > Dave
> >
> >
> >> Oleksandr Natalenko (1):
> >>   runq: display relative lag of each CPU
> >>
> >>  help.c |  4 +++-
> >>  task.c | 76
> >>  +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
> >>  2 files changed, 78 insertions(+), 2 deletions(-)
> >>
> >> --
> >> 2.15.0
> >>
> >>
> 
> 
> 
> --
> Best regards,
>   Oleksandr Natalenko (post-factum)
>   Software Maintenance Engineer
>