From: valdis.kletnieks@vt.edu
To: Pintu Agarwal <pintu.ping@gmail.com>
Cc: mark.rutland@arm.com, Jungseok Lee <jungseoklee85@gmail.com>,
kernelnewbies@kernelnewbies.org, catalin.marinas@arm.com,
Sungjinn Chung <barami97@gmail.com>,
will.deacon@arm.com, open list <linux-kernel@vger.kernel.org>,
Russell King - ARM Linux <linux@armlinux.org.uk>,
Takahiro Akashi <takahiro.akashi@linaro.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [ARM64] Printing IRQ stack usage information
Date: Fri, 16 Nov 2018 13:31:51 -0500 [thread overview]
Message-ID: <15703.1542393111@turing-police.cc.vt.edu> (raw)
Message-ID: <20181116183151.m00GrrFPudWbycxd_WsGW-d-6-rafhTS7_iQir35F9U@z> (raw)
In-Reply-To: <CAOuPNLiX0zhxiRAx03YjVU6cocwWbgY9naxeYPRKmT+3PoGhRw@mail.gmail.com>
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On Fri, 16 Nov 2018 23:13:48 +0530, Pintu Agarwal said:
> On Fri, Nov 16, 2018 at 10:16 PM <valdis.kletnieks@vt.edu> wrote:
> > Congrats. You just re-invented DEBUG_STACK_USAGE, which just keeps a high-water mark
> > for stack usage.
>
> So, you mean to say, my implementation is good enough to get the
> irq_stack usage, from the interrupt handler ?
No - your code doesn't keep a high-water mark (which should probably be
hooked into the IRQ exit code.
> But my concern is that if I dump it from irq handler, I will get
> information only for the current cpu.
> How do I store and get the information for all the cpu from the boot time ?
Make the high-water mark a per-cpu variable.
> From where do I call my dump_irq_stack_info() [some where during the
> entry/exit part of the irq handler], so that I could dump information
> for all the handler at boot time itself ?
No, you don't do a dump-stack during entry/exit. You just maintain a high-water
value in the exit, and then you create a /proc/something or similar that when
read does a 'foreach CPU do print_high_water_irq'.
> Like I would to capture these information:
> - What was the name of the handler ?
> - Which cpu was executing it ?
> - How much irq stack (max value, same like high water mark) were used
> at that time ?
First, do the easy part and find out if you even *care* once you see actual
numbers. If your IRQ stack is 8K but you never use more than 2500 bytes,
do you *really* care about the name of the handler anymore?
Also, see the code for /proc/interrupts to see how it keeps track of the
interrupts per CPU - maybe all you need to do is change each entry from
a 'count' to 'count, highwater'.
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next prev parent reply other threads:[~2018-11-16 18:32 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-15 13:22 [ARM64] Printing IRQ stack usage information Pintu Agarwal
2018-11-15 13:22 ` Pintu Agarwal
2018-11-15 16:49 ` valdis.kletnieks at vt.edu
2018-11-15 16:49 ` valdis.kletnieks
2018-11-16 6:14 ` Pintu Agarwal
2018-11-16 6:14 ` Pintu Agarwal
2018-11-16 11:33 ` valdis.kletnieks at vt.edu
2018-11-16 11:33 ` valdis.kletnieks
2018-11-16 14:40 ` Pintu Agarwal
2018-11-16 14:40 ` Pintu Agarwal
2018-11-16 16:46 ` valdis.kletnieks at vt.edu
2018-11-16 16:46 ` valdis.kletnieks
2018-11-16 17:43 ` Pintu Agarwal
2018-11-16 17:43 ` Pintu Agarwal
2018-11-16 18:31 ` valdis.kletnieks at vt.edu [this message]
2018-11-16 18:31 ` valdis.kletnieks
2018-11-17 13:06 ` Pintu Agarwal
2018-11-17 13:06 ` Pintu Agarwal
2018-11-20 12:51 ` Pintu Agarwal
2018-11-20 12:51 ` Pintu Agarwal
2018-11-20 19:03 ` valdis.kletnieks at vt.edu
2018-11-20 19:03 ` valdis.kletnieks
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