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    SubjectRe: [RFC PATCH 2/3 v2] perf: Implement Nehalem uncore pmu
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    On Sun, 2010-11-21 at 20:46 +0800, Andi Kleen wrote:
    > >
    > > 2. Uncore pmu NMI handling
    > >
    > > All the 4 cores are programmed to receive uncore counter overflow
    > > interrupt. The NMI handler(running on 1 of the 4 cores) handle all
    > > counters enabled by all 4 cores.
    >
    > Really for uncore monitoring there is no need to use an NMI handler.
    > You can't profile a core anyways, so you can just delay the reporting
    > a little bit. It may simplify the code to not use one here
    > and just use an ordinary handler.

    OK, I can use on ordinary interrupt handler here.

    >
    > In general since there is already much trouble with overloaded
    > NMI events avoiding new NMIs is a good idea.
    >
    >
    >
    > > +
    > > +static struct node_hw_events *uncore_events[MAX_NUMNODES];
    >
    > Don't declare static arrays with MAX_NUMNODES, that number can be
    > very large and cause unnecessary bloat. Better use per CPU data or similar
    > (e.g. with alloc_percpu)

    I really need is a per physical cpu data here, is alloc_percpu enough?

    >
    > > + /*
    > > + * The hw event starts counting from this event offset,
    > > + * mark it to be able to extra future deltas:
    > > + */
    > > + local64_set(&hwc->prev_count, (u64)-left);
    >
    > Your use of local* seems dubious. That is only valid if it's really
    > all on the same CPU. Is that really true?

    Good catch! That is not true.

    The interrupt handler is running on one core and the
    data(hwc->prev_count) maybe on another core.

    Any idea to set this cross-core data?

    >
    > > +static int uncore_pmu_add(struct perf_event *event, int flags)
    > > +{
    > > + int node = numa_node_id();
    >
    > this should be still package id

    Understand, this is in my TODO.

    >
    > > + /* Check CPUID signatures: 06_1AH, 06_1EH, 06_1FH */
    > > + model = eax.split.model | (eax.split.ext_model << 4);
    > > + if (eax.split.family != 6 || (model != 0x1A && model != 0x1E && model !=
    > > 0x1F))
    > > + return;
    >
    > You can just get that from boot_cpu_data, no need to call cpuid

    Nice, will use it.

    >
    > > +#include <linux/perf_event.h>
    > > +#include <linux/capability.h>
    > > +#include <linux/notifier.h>
    > > +#include <linux/hardirq.h>
    > > +#include <linux/kprobes.h>
    > > +#include <linux/module.h>
    > > +#include <linux/kdebug.h>
    > > +#include <linux/sched.h>
    > > +#include <linux/uaccess.h>
    > > +#include <linux/slab.h>
    > > +#include <linux/highmem.h>
    > > +#include <linux/cpu.h>
    > > +#include <linux/bitops.h>
    >
    > Do you really need all these includes?

    Only

    #include <linux/perf_event.h>
    #include <linux/kprobes.h>
    #include <linux/hardirq.h>
    #include <linux/slab.h>

    are needed.

    Thanks for the comments.
    Lin Ming




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