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    SubjectRe: [PATCH 2/3] perf/x86/pebs: add workaround for broken OVFL status on HSW
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    On Tue, Mar 8, 2016 at 9:34 PM, Stephane Eranian <eranian@google.com> wrote:
    > On Tue, Mar 8, 2016 at 1:13 PM, Stephane Eranian <eranian@google.com> wrote:
    >> Hi,
    >>
    >> On Tue, Mar 8, 2016 at 1:07 PM, Peter Zijlstra <peterz@infradead.org> wrote:
    >>> On Tue, Mar 08, 2016 at 12:59:23PM -0800, Stephane Eranian wrote:
    >>>> hi,
    >>>>
    >>>> On Mon, Mar 7, 2016 at 12:25 PM, Peter Zijlstra <peterz@infradead.org> wrote:
    >>>> >
    >>>> > On Mon, Mar 07, 2016 at 07:27:31PM +0100, Jiri Olsa wrote:
    >>>> > > On Mon, Mar 07, 2016 at 01:18:40PM +0100, Peter Zijlstra wrote:
    >>>> > > > On Mon, Mar 07, 2016 at 11:24:13AM +0100, Peter Zijlstra wrote:
    >>>> > > >
    >>>> > > > > I suspect Andi is having something along:
    >>>> > > > >
    >>>> > > > > lkml.kernel.org/r/1445458568-16956-1-git-send-email-andi@firstfloor.org
    >>>> > > > >
    >>>> > > > > applied to his tree.
    >>>> > > >
    >>>> > > > OK, I munged a bunch of patches together, please have a hard look at the
    >>>> > > > end result found in:
    >>>> > > >
    >>>> > > > git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git perf/core
    >>>> > > >
    >>>>
    >>>> I ran this kernel on Haswell. Even with Andi's fixes the problem I identified is
    >>>> still there, so my patch is still needed.
    >>>
    >>> Right, your patch should be included in that kernel, or did I make a
    >>> royal mess of things?
    >>>
    >> No, it is as expected for the OVF PMI fix.
    >>
    >>> I put Andi's late status ack on top of your patch.
    >>>
    > Ok, I ran into a problem on Broadwell with your branch with Andi's
    > patches. I see

    Sorry this is with tip.git and not your branch. Will try with it too.

    > a problem which had disappeared since SandyBridge:
    >
    > 11551.128422] ------------[ cut here ]------------
    > [11551.128435] WARNING: CPU: 3 PID: 12114 at
    > arch/x86/events/intel/core.c:1868 intel_pmu_handle_irq+0x2da/0x4b0()
    > [11551.128437] perfevents: irq loop stuck!
    > [11551.128469] <NMI> [<ffffffff81663975>] dump_stack+0x4d/0x63
    > [11551.128479] [<ffffffff810b8657>] warn_slowpath_common+0x97/0xe0
    > [11551.128482] [<ffffffff810b8756>] warn_slowpath_fmt+0x46/0x50
    > [11551.128486] [<ffffffff8100b6ca>] intel_pmu_handle_irq+0x2da/0x4b0
    > [11551.128491] [<ffffffff81004569>] perf_event_nmi_handler+0x39/0x60
    > [11551.128494] [<ffffffff8107be61>] nmi_handle+0x61/0x110
    > [11551.128497] [<ffffffff8107c684>] default_do_nmi+0x44/0x110
    > [11551.128500] [<ffffffff8107c827>] do_nmi+0xd7/0x140
    > [11551.128504] [<ffffffff8166e127>] end_repeat_nmi+0x1a/0x1e
    > [11551.128507] [<ffffffff81009dd6>] ? native_write_msr+0x6/0x30
    > [11551.128510] [<ffffffff81009dd6>] ? native_write_msr+0x6/0x30
    > [11551.128514] [<ffffffff81009dd6>] ? native_write_msr+0x6/0x30
    > [11551.128515] <<EOE>> [<ffffffff8100b385>] ?
    > intel_pmu_enable_event+0x215/0x230
    > [11551.128520] [<ffffffff81005a0d>] x86_pmu_start+0x8d/0x120
    > [11551.128523] [<ffffffff810061db>] x86_pmu_enable+0x27b/0x2f0
    > [11551.128527] [<ffffffff8118d63d>] perf_pmu_enable+0x1d/0x30
    > [11551.128530] [<ffffffff81191bca>] ctx_resched+0x5a/0x70
    > [11551.128532] [<ffffffff81191d8c>] __perf_event_enable+0x1ac/0x210
    > [11551.128537] [<ffffffff81188f81>] event_function+0xa1/0x170
    > [11551.128540] [<ffffffff811899b0>] ? perf_duration_warn+0x70/0x70
    > [11551.128543] [<ffffffff811899f7>] remote_function+0x47/0x60
    > [11551.128547] [<ffffffff8112a178>] generic_exec_single+0xa8/0xb0
    > [11551.128550] [<ffffffff811899b0>] ? perf_duration_warn+0x70/0x70
    > [11551.128553] [<ffffffff811899b0>] ? perf_duration_warn+0x70/0x70
    > [11551.128555] [<ffffffff8112a298>] smp_call_function_single+0xa8/0x100
    > [11551.128559] [<ffffffff8118aec4>] event_function_call+0x84/0x100
    > [11551.128561] [<ffffffff81191be0>] ? ctx_resched+0x70/0x70
    > [11551.128564] [<ffffffff81191be0>] ? ctx_resched+0x70/0x70
    > [11551.128566] [<ffffffff81188ee0>] ? perf_ctx_lock+0x30/0x30
    > [11551.128570] [<ffffffff8118b050>] _perf_event_enable+0x60/0x80
    > [11551.128572] [<ffffffff8118fc61>] perf_ioctl+0x271/0x3e0
    >
    > The infinite loop in the irq handler!
    >
    > But here it seems there is a race with a perf_events ioctl() to likely
    > reset the period.
    > I am not using the perf tool here just running a self-monitoring task.
    >
    >
    >>> Also note, Ingo merged most of those patches today, all except the top
    >>> 3, because Andi wanted to double check something.
    >>

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