Messages in this thread | | | Date | Tue, 21 Jun 2011 19:26:16 +0200 | Subject | Re: [RFC -tip] perf, x86: Add PERF_COUNT_HW_NMI_WATCHDOG event v2 | From | Stephane Eranian <> |
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On Tue, Jun 21, 2011 at 7:23 PM, Cyrill Gorcunov <gorcunov@gmail.com> wrote: > On Tue, Jun 21, 2011 at 07:10:05PM +0200, Stephane Eranian wrote: > ... >> > >> > The key here is that we use that named non-sleeping ticks (as oprofile >> > did) for nmi-watchdog and it allows us to free "cpu-cycles" counter for >> > user needs. Of course we pick up one counter for this but it doesn't intersect >> > with "cpu-cycles" counter (because counters are grouped and can count only >> > specified events in each group). Stepane, should I post more details? >> > >> Ok, so you're using a different PMU event for the watchdog. But then, in this >> case why not simply change kernel/watchdog.c to hardcode something specific >> for P4, i.e, change the wd_hw_attr.config/type fields to match the >> event you want. > > It doesn't change things much. Of course I can put some specifics into > .config but where is the guarantee some new generic event would not ever > intersect with it. I know (for example) we could reserve -1ULL for this > event but again where is the guarantee that it will never ever be used > system wide in future for some different event? > I am not talking about a new generic PMU event. I am talking about you hardcoding a raw event in the callback: type = PERF_TYPE_RAW, config=0x003c.
> So I need some event-id in which I may be sure it will never be > used for different purpose. > >> You could create a arch specific callback to setup config/type. >> >> I don't think it makes sense to expose yet another generic PMU event, especially >> given the name you gave to it and what it actually does. People might wonder >> what good is that for? > > Cyrill > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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