linux-kernel - Re: [PATCH v2 -tip] perf: x86, add SandyBridge support

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Date:	Tue, 1 Mar 2011 10:39:26 +0100
From:	Stephane Eranian <eranian@...gle.com>
To:	Lin Ming <ming.m.lin@...el.com>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...e.hu>, Andi Kleen <andi@...stfloor.org>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 -tip] perf: x86, add SandyBridge support

On Tue, Mar 1, 2011 at 9:57 AM, Stephane Eranian <eranian@...gle.com> wrote:
> On Tue, Mar 1, 2011 at 9:45 AM, Lin Ming <ming.m.lin@...el.com> wrote:
>> On Tue, 2011-03-01 at 15:43 +0800, Stephane Eranian wrote:
>>> On Mon, Feb 28, 2011 at 10:15 AM, Peter Zijlstra <a.p.zijlstra@...llo.nl> wrote:
>>> > On Mon, 2011-02-28 at 15:22 +0800, Lin Ming wrote:
>>> >> This patch adds basic SandyBridge support, including hardware cache
>>> >> events and PEBS events support.
>>> >>
>>> >> LLC-* hareware cache events don't work for now, it depends on the
>>> >> offcore patches.
>>> >
>>> > What's the status of those, Stephane reported some problems last I
>>> > remember?
>>> >
>>> I tried the trick I mentioned and it seems to work.
>>>
>>> Something like below with hwc->extra_alloc.
>>> Could probably find a better name for that field.
>>
>> Stephane,
>>
>> I'll integrate below changes to the offcore patches, OK?
>>
> Let me try one more test on this.
> I want to show the case the caused the problem in the first place.
>

There you go:

$ task -e offcore_response_0:DMND_DATA_RD:local_dram -e
offcore_response_0:DMND_DATA_RD:local_dram noploop 1

Here the two instances of offcore_response are in two different event groups.
I instrumented get/put percore constraint routines. get1 is where you do the
first allocation, get2 is where you do ref++.

The scheduling algorithm will do:
  - submit 1st group
  - schedule 1st group
  - submit 2nd group
  - schedule 1st + 2nd group

Which results in the following trace:

[  109.855713] CPU0 get1 cfg=1301b7 ref=1
[  109.855717] CPU0 get2 cfg=1301b7 ref=2
[  109.855718] CPU0 get2 cfg=1301b7 ref=3 <-- this one is bogus
[  109.856606] CPU0 put cfg=1301b7 ref=2
[  109.856609] CPU0 put cfg=1301b7 ref=1  <- don't free the resource

[  109.856616] CPU0 get2 cfg=1301b7 ref=2
[  109.856619] CPU0 get2 cfg=1301b7 ref=3
[  109.856622] CPU0 get2 cfg=1301b7 ref=4
[  110.742151] CPU0 put cfg=1301b7 ref=3
[  110.742154] CPU0 put cfg=1301b7 ref=2

[  110.742160] CPU0 get2 cfg=1301b7 ref=3
[  110.742161] CPU0 get2 cfg=1301b7 ref=4
[  110.742163] CPU0 get2 cfg=1301b7 ref=5
[  110.854448] CPU0 put cfg=1301b7 ref=4
[  110.854450] CPU0 put cfg=1301b7 ref=3
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