From: valdis.kletnieks@vt.edu (valdis.kletnieks at vt.edu) To: kernelnewbies@lists.kernelnewbies.org Subject: [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) In-Reply-To: <CAOuPNLiX0zhxiRAx03YjVU6cocwWbgY9naxeYPRKmT+3PoGhRw@mail.gmail.com> 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'. -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 486 bytes Desc: not available URL: <http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20181116/1040e3c1/attachment.sig>
WARNING: multiple messages have this Message-ID (diff)
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> [-- Attachment #1.1: Type: text/plain, Size: 1684 bytes --] 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'. [-- Attachment #1.2: Type: application/pgp-signature, Size: 486 bytes --] [-- Attachment #2: Type: text/plain, Size: 170 bytes --] _______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
next prev parent reply other threads:[~2018-11-16 18:31 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
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=15703.1542393111@turing-police.cc.vt.edu \ --to=valdis.kletnieks@vt.edu \ --cc=kernelnewbies@lists.kernelnewbies.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).