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Subject: Re: [PATCH v4 2/2] arm64: Expand the stack trace feature to support IRQ stack
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From: Jungseok Lee <jungseoklee85@gmail.com>
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Date: Thu, 15 Oct 2015 23:24:57 +0900
Cc: takahiro.akashi@linaro.org, catalin.marinas@arm.com, will.deacon@arm.com,
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To: James Morse <james.morse@arm.com>
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On Oct 9, 2015, at 11:24 PM, James Morse wrote:

Hi James,

[ ... ]

> I think unwind_frame() needs to walk the irq stack too. [2] is an example
> of perf tracing back to userspace, (and there are patches on the list to
> do/fix this), so we need to walk back to the start of the first stack for
> the perf accounting to be correct.

I plan to do re-spin this series without [PATCH 2/2] since 1) Akashi's
approach looks better than mine and 2) you have the perf patches for [2].
This would help us to move forward.

Thoughts?

[ ... ]

> [0] sudo ./perf record -e mem:<address of __do_softirq()>:x -ag -- sleep 10
> [1] sudo ./perf report --call-graph --stdio
> [2] http://www.brendangregg.com/FlameGraphs/cpuflamegraphs.html

Best Regards
Jungseok Lee

From mboxrd@z Thu Jan  1 00:00:00 1970
From: jungseoklee85@gmail.com (Jungseok Lee)
Date: Thu, 15 Oct 2015 23:24:57 +0900
Subject: [PATCH v4 2/2] arm64: Expand the stack trace feature to support
 IRQ stack
In-Reply-To: <5617CE26.10604@arm.com>
References: <1444231692-32722-1-git-send-email-jungseoklee85@gmail.com>
 <1444231692-32722-3-git-send-email-jungseoklee85@gmail.com>
 <5617CE26.10604@arm.com>
Message-ID: <179A25A2-C346-46C0-93D1-BABD4B6CB401@gmail.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Oct 9, 2015, at 11:24 PM, James Morse wrote:

Hi James,

[ ... ]

> I think unwind_frame() needs to walk the irq stack too. [2] is an example
> of perf tracing back to userspace, (and there are patches on the list to
> do/fix this), so we need to walk back to the start of the first stack for
> the perf accounting to be correct.

I plan to do re-spin this series without [PATCH 2/2] since 1) Akashi's
approach looks better than mine and 2) you have the perf patches for [2].
This would help us to move forward.

Thoughts?

[ ... ]

> [0] sudo ./perf record -e mem:<address of __do_softirq()>:x -ag -- sleep 10
> [1] sudo ./perf report --call-graph --stdio
> [2] http://www.brendangregg.com/FlameGraphs/cpuflamegraphs.html

Best Regards
Jungseok Lee