Re: [PATCH 4/5] monitor: removed cpustats command

[Greg Kurz]

On Thu, 27 May 2021 08:24:40 -0300
Bruno Piazera Larsen <bruno.larsen@eldorado.org.br> wrote:

> 
> On 27/05/2021 05:30, Greg Kurz wrote:
> > On Thu, 27 May 2021 09:09:55 +0100
> > "Dr. David Alan Gilbert" <dgilbert@redhat.com> wrote:
> >
> >> * Greg Kurz (groug@kaod.org) wrote:
> >>> On Wed, 26 May 2021 17:21:03 -0300
> >>> "Bruno Larsen (billionai)" <bruno.larsen@eldorado.org.br> wrote:
> >>>
> >>>> Since ppc was the last architecture to collect these statistics and
> >>>> it is currently phasing this collection out, the command that would query
> >>>> this information is being removed.
> >>>>
> >>> So this is removing an obviously user visible feature. This should be
> >>> mentioned in docs/system/removed-features.rst... but, wait, I don't
> >>> see anything for it in docs/system/deprecated.rst. This is dropping
> >>> a feature without following the usual deprecation policy, i.e.
> >>> marking the feature as deprecated and only remove it 2 QEMU versions
> >>> later. Any justification for that ?
> 
> The command called a function that ultimately called an empty callback 
> unless you changed target/ppc/translate.c and removed the comments 
> around #define DO_PPC_STATISTICS. And like I mentioned in the cover 
> letter (which may not have been CC'ed to you, sorry) ppc was the last 
> architecture to support this feature while they were using the legacy 
> decode system, but as they move to decodetree, this data wouldn't even 
> be collected.
> 
> That's the justification, basically.
> 

So to sum up, this HMP command doesn't produce any output with upstream
QEMU. Add a section in docs/system/removed-features.rst and just mention
that. Not worth reposting the full series just for that. This can be done
in a followup patch.

> >> As long as the command really isn't useful any more, I wouldn't object
> >> to that from an HMP point of view.
> >>
> > Ok then this should be documented in docs/system/removed-features.rst at
> > least.
> Sure, will send a patch later today with the update
> >
> >> Dave
> >>
> >>> David,
> >>>
> >>> Unrelated, I saw that you already applied this to ppc-for-6.1 on gitlab
> >>> but the commit title appears to be broken:
> >>>
> >>> '65;6401;1cmonitor: removed cpustats command
> >>>
> >>> https://gitlab.com/dgibson/qemu/-/commit/532be563eae6b8ae834ff7e9ebb1428f53569a69
> >>>
> >>>> Suggested-by: Richard Henderson <richard.henderson@linaro.org>
> >>>> Signed-off-by: Bruno Larsen (billionai) <bruno.larsen@eldorado.org.br>
> >>>> ---
> >>>>   hmp-commands-info.hx | 13 -------------
> >>>>   monitor/misc.c       | 11 -----------
> >>>>   2 files changed, 24 deletions(-)
> >>>>
> >>>> diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
> >>>> index ab0c7aa5ee..b2347a6aea 100644
> >>>> --- a/hmp-commands-info.hx
> >>>> +++ b/hmp-commands-info.hx
> >>>> @@ -500,19 +500,6 @@ SRST
> >>>>       Show the current VM UUID.
> >>>>   ERST
> >>>>   
> >>>> -    {
> >>>> -        .name       = "cpustats",
> >>>> -        .args_type  = "",
> >>>> -        .params     = "",
> >>>> -        .help       = "show CPU statistics",
> >>>> -        .cmd        = hmp_info_cpustats,
> >>>> -    },
> >>>> -
> >>>> -SRST
> >>>> -  ``info cpustats``
> >>>> -    Show CPU statistics.
> >>>> -ERST
> >>>> -
> >>>>   #if defined(CONFIG_SLIRP)
> >>>>       {
> >>>>           .name       = "usernet",
> >>>> diff --git a/monitor/misc.c b/monitor/misc.c
> >>>> index f3a393ea59..1539e18557 100644
> >>>> --- a/monitor/misc.c
> >>>> +++ b/monitor/misc.c
> >>>> @@ -369,17 +369,6 @@ static void hmp_info_history(Monitor *mon, const 
> >>>> QDict *qdict)
> >>>>       }
> >>>>   }
> >>>>   
> >>>> -static void hmp_info_cpustats(Monitor *mon, const QDict *qdict)
> >>>> -{
> >>>> -    CPUState *cs = mon_get_cpu(mon);
> >>>> -
> >>>> -    if (!cs) {
> >>>> -        monitor_printf(mon, "No CPU available\n");
> >>>> -        return;
> >>>> -    }
> >>>> -    cpu_dump_statistics(cs, 0);
> >>>> -}
> >>>> -
> >>>>   static void hmp_info_trace_events(Monitor *mon, const QDict *qdict)
> >>>>   {
> >>>>       const char *name = qdict_get_try_str(qdict, "name");