From: Anshuman Khandual <khandual@linux.vnet.ibm.com>
To: Michael Ellerman <michael@ellerman.id.au>
Cc: linuxppc-dev@ozlabs.org, mikey@neuling.org
Subject: Re: [PATCH] powerpc, perf: Configure BHRB filter before enabling PMU interrupts
Date: Wed, 16 Oct 2013 10:00:36 +0530 [thread overview]
Message-ID: <525E166C.5070407@linux.vnet.ibm.com> (raw)
In-Reply-To: <20131014061958.GA8300@concordia>
On 10/14/2013 11:49 AM, Michael Ellerman wrote:
> On Fri, Oct 11, 2013 at 10:02:28AM +0530, Anshuman Khandual wrote:
>> On 10/11/2013 07:41 AM, Michael Ellerman wrote:
>>> On Thu, Oct 10, 2013 at 02:20:22PM +0530, Anshuman Khandual wrote:
>>>
>>>> Even I think this is not right. Instruction sampling should have been
>>>> enabled before we enable PMU interrupts. Else there is a small window
>>>> of time where we could have the PMU enabled with events (which requires
>>>> sampling) without the sampling itself being enabled in MMCRA.
>>>
>>> Yes I agree. That's a separate bug, which we'll need to test on all the book3s
>>> platforms we have perf support for.
>>
>> Okay, I guess any platform which supports sampling will definitely want to have
>> it enabled before we can set the events to count on PMU. Can you think of any
>> problem which can arise if we move it before the enabling the PMU back ? Else
>> we can fix this easily.
>
> In theory it should be a trivial change. But hardware can behave in
> strange ways, it's possible on some old chip we need to do it the
> current way for some reason.
>
> So although I don't think it will be a problem, it could be, so we
> will need to test it thoroughly.
So which are the HW chips, you would like to test this fix for possible problems ?
next prev parent reply other threads:[~2013-10-16 4:31 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-07 4:30 [PATCH] powerpc, perf: Configure BHRB filter before enabling PMU interrupts Anshuman Khandual
2013-10-08 4:21 ` Michael Ellerman
2013-10-08 7:21 ` Anshuman Khandual
2013-10-09 1:21 ` Michael Ellerman
2013-10-09 4:46 ` Anshuman Khandual
2013-10-09 6:03 ` Michael Ellerman
2013-10-10 8:50 ` Anshuman Khandual
2013-10-11 2:11 ` Michael Ellerman
2013-10-11 4:32 ` Anshuman Khandual
2013-10-14 6:19 ` Michael Ellerman
2013-10-16 4:30 ` Anshuman Khandual [this message]
2013-12-13 6:46 ` Anshuman Khandual
-- strict thread matches above, loose matches on Subject: below --
2013-12-18 2:14 Michael Ellerman
2013-12-18 3:41 ` Anshuman Khandual
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