Messages in this thread | | | Date | Mon, 16 Jan 2012 16:03:07 +0100 | From | Oleg Nesterov <> | Subject | Re: [GIT PULL] tracing: make signal tracepoints more useful |
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On 01/16, Ingo Molnar wrote: > > * Oleg Nesterov <oleg@redhat.com> wrote: > > > > 2/2 looks like a bugfix to me, but 1/2 changes the output from > > > trace_signal_generate() and removes trace_signal_overflow_fail. > > > In essence the change is: > > > > > > - TP_printk("sig=%d errno=%d code=%d comm=%s pid=%d", > > > + TP_printk("sig=%d errno=%d code=%d comm=%s pid=%d grp=%d res=%d", > > > > > I've also Cc:-ed Masami-san who appears to have introduced most > of this trace information.
Thanks... although he is already cc'ed, may be I used the wrong email.
> Looks good to me at a first (quick) sight, except this bit > which changes the ABI: > > > > - TP_printk("sig=%d errno=%d code=%d comm=%s pid=%d", > > > + TP_printk("sig=%d errno=%d code=%d comm=%s pid=%d grp=%d res=%d", > > That's not how we change tracepoints generally - we add a new > one and eventually phase out the old one.
Well, "vmscan/trace: Add 'file' info to trace_mm_vmscan_lru_isolate()" ea4d349f adds the new field too. In fact this patch (floating in -mm) plus the previous discussion convinced me we should go this way.
> Which apps/tools rely > on the old tracepoint? If it's exactly zero apps then we might > be able to change it, but this needs to be investigated.
If only I knew. How can we investigate this? Hopefully nothing relies on the old tracepoint, but who knows.
OK. So we should add the new tracepoint. Looks a bit ugly, but I understand your concerns.
Say, trace_send_signal(sig, info, t, group, result), OK?
Seiji, please double check this is all you need, it won't be simply to change this tracepoint again. While we are adding the new one, we can add/change something in TP_STRUCT__entry if you think this is needed.
> Note, it might make sense to send these as two patches to lkml > with me Cc:-ed to avoid any github trust issues, i can apply > them and push them to Linus.
Ingo, I sent them 3 times and you were cc'ed ;)
Thanks!
Oleg.
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