Messages in this thread | | | Date | Fri, 26 Nov 2010 13:15:16 +0800 | Subject | Re: [RFC PATCH 2/3 v2] perf: Implement Nehalem uncore pmu | From | Lin Ming <> |
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On Tue, Nov 23, 2010 at 6:17 PM, Stephane Eranian <eranian@google.com> wrote: > Lin, > > On Sun, Nov 21, 2010 at 1:01 PM, Lin Ming <ming.m.lin@intel.com> wrote: >> +static void uncore_pmu_enable_all(void) >> +{ >> + u64 ctrl; >> + >> + /* >> + * (0xFULL << 48): 1 of the 4 cores can receive NMI each time >> + * but we don't know which core will receive the NMI when overflow happens >> + */ > > That does not sound right. If you set bit 48-51 to 1, then all 4 cores > will receive EVERY > interrupt, i.e., it's a broadcast. That seems to contradict your > comment: 1 of the 4. Unless > you meant, they all get the interrupt and one will handle it, the > other will find nothing to > process. But I don't see the atomic op that would make this true in > uncore_handle_irq().
Stephane,
The interrupt model is strange, it behaves differently when HT on/off.
If HT is off, all 4 cores will receive every interrupt, i.e., it's a broadcast.
If HT is on, only 1 of the 4 cores will receive the interrupt(both Threads in that core receive the interrupt), and it can't be determined which core will receive the interrupt.
Did you ever observe this?
> > I also think that if you want all processors to receive the > interrupts, then the mask should > be 0xff when HT is on. The manual is rather obscure on this, but it > does make sense.
I tried to set the mask 0xff when HT is on, but kernel panics, because the reserve bits are set.
Thanks, Lin Ming
> > >> + ctrl = ((1 << UNCORE_NUM_GENERAL_COUNTERS) - 1) | (0xFULL << 48); >> + ctrl |= MSR_UNCORE_PERF_GLOBAL_CTRL_EN_FC0; >> + >> + /* >> + * Freeze the uncore pmu on overflow of any uncore counter. >> + * This makes unocre NMI handling easier. >> + */ >> + ctrl |= MSR_UNCORE_PERF_GLOBAL_CTRL_PMI_FRZ; >> + >> + wrmsrl(MSR_UNCORE_PERF_GLOBAL_CTRL, ctrl); >> +} >> + > -- -- 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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