From: Steven Rostedt <rostedt@goodmis.org>
To: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Jungseok Lee <jungseoklee85@gmail.com>,
catalin.marinas@arm.com, will.deacon@arm.com, olof@lixom.net,
broonie@kernel.org, david.griego@linaro.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [RFC 2/3] arm64: refactor save_stack_trace()
Date: Thu, 16 Jul 2015 23:21:28 -0400 [thread overview]
Message-ID: <20150716232128.1a887a9f@grimm.local.home> (raw)
In-Reply-To: <55A86D50.9060407@linaro.org>
On Fri, 17 Jul 2015 11:49:52 +0900
AKASHI Takahiro <takahiro.akashi@linaro.org> wrote:
> > -
> > - if (using_ftrace_ops_list_func())
> > - max_stack_trace.skip = 4;
> > - else
> > - max_stack_trace.skip = 3;
> > + max_stack_trace.skip = 3;
>
> I don't think this last line is necessary because we will skip all
> the functions anyway below:
I put this back more as an optimization as it is already known that it
takes at least three calls to get to this point. Unless of course gcc
decides to inline them. But currently I don't see that.
>
> > save_stack_trace(&max_stack_trace);
> >
> > - /*
> > - * Add the passed in ip from the function tracer.
> > - * Searching for this on the stack will skip over
> > - * most of the overhead from the stack tracer itself.
> > - */
> > - stack_dump_trace[0] = ip;
> > - max_stack_trace.nr_entries++;
> > + /* Skip over the overhead of the stack tracer itself */
> > + for (i = 0; i < max_stack_trace.nr_entries; i++) {
> > + if (stack_dump_trace[i] == ip)
> > + break;
> > + }
>
> here. Now "i" indicates the start point, excepting tracer functions,
> and "x" will eventually represent the exact number of functions
> that we are interested in after searching the stack.
>
> To calc "stack_max_size" correctly, we should change the line:
> if (unlikely(tracer_frame) && i == 1) {
> to
> if (unlikely(tracer_frame)) {
Good catch, I'll fix that!
-- Steve
>
> With these two changes applied, the issues Jungseok mentioned will be
> fixed.
>
WARNING: multiple messages have this Message-ID (diff)
From: rostedt@goodmis.org (Steven Rostedt)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC 2/3] arm64: refactor save_stack_trace()
Date: Thu, 16 Jul 2015 23:21:28 -0400 [thread overview]
Message-ID: <20150716232128.1a887a9f@grimm.local.home> (raw)
In-Reply-To: <55A86D50.9060407@linaro.org>
On Fri, 17 Jul 2015 11:49:52 +0900
AKASHI Takahiro <takahiro.akashi@linaro.org> wrote:
> > -
> > - if (using_ftrace_ops_list_func())
> > - max_stack_trace.skip = 4;
> > - else
> > - max_stack_trace.skip = 3;
> > + max_stack_trace.skip = 3;
>
> I don't think this last line is necessary because we will skip all
> the functions anyway below:
I put this back more as an optimization as it is already known that it
takes at least three calls to get to this point. Unless of course gcc
decides to inline them. But currently I don't see that.
>
> > save_stack_trace(&max_stack_trace);
> >
> > - /*
> > - * Add the passed in ip from the function tracer.
> > - * Searching for this on the stack will skip over
> > - * most of the overhead from the stack tracer itself.
> > - */
> > - stack_dump_trace[0] = ip;
> > - max_stack_trace.nr_entries++;
> > + /* Skip over the overhead of the stack tracer itself */
> > + for (i = 0; i < max_stack_trace.nr_entries; i++) {
> > + if (stack_dump_trace[i] == ip)
> > + break;
> > + }
>
> here. Now "i" indicates the start point, excepting tracer functions,
> and "x" will eventually represent the exact number of functions
> that we are interested in after searching the stack.
>
> To calc "stack_max_size" correctly, we should change the line:
> if (unlikely(tracer_frame) && i == 1) {
> to
> if (unlikely(tracer_frame)) {
Good catch, I'll fix that!
-- Steve
>
> With these two changes applied, the issues Jungseok mentioned will be
> fixed.
>
next prev parent reply other threads:[~2015-07-17 3:20 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-13 5:29 [RFC 0/3] arm64: ftrace: fix incorrect output from stack tracer AKASHI Takahiro
2015-07-13 5:29 ` AKASHI Takahiro
2015-07-13 5:29 ` [RFC 1/3] ftrace: adjust a function's pc to search for in check_stack() for arm64 AKASHI Takahiro
2015-07-13 5:29 ` AKASHI Takahiro
2015-07-13 15:24 ` Steven Rostedt
2015-07-13 15:24 ` Steven Rostedt
2015-07-15 0:22 ` AKASHI Takahiro
2015-07-15 0:22 ` AKASHI Takahiro
2015-07-13 5:29 ` [RFC 2/3] arm64: refactor save_stack_trace() AKASHI Takahiro
2015-07-13 5:29 ` AKASHI Takahiro
2015-07-14 12:47 ` Jungseok Lee
2015-07-14 12:47 ` Jungseok Lee
2015-07-14 13:31 ` Steven Rostedt
2015-07-14 13:31 ` Steven Rostedt
2015-07-15 0:20 ` AKASHI Takahiro
2015-07-15 0:20 ` AKASHI Takahiro
2015-07-15 2:51 ` Steven Rostedt
2015-07-15 2:51 ` Steven Rostedt
2015-07-15 11:41 ` AKASHI Takahiro
2015-07-15 11:41 ` AKASHI Takahiro
2015-07-15 14:55 ` Steven Rostedt
2015-07-15 14:55 ` Steven Rostedt
2015-07-15 16:13 ` Steven Rostedt
2015-07-15 16:13 ` Steven Rostedt
2015-07-16 0:27 ` AKASHI Takahiro
2015-07-16 0:27 ` AKASHI Takahiro
2015-07-16 1:08 ` AKASHI Takahiro
2015-07-16 1:08 ` AKASHI Takahiro
2015-07-16 1:38 ` Steven Rostedt
2015-07-16 1:38 ` Steven Rostedt
2015-07-17 10:46 ` Will Deacon
2015-07-17 10:46 ` Will Deacon
2015-07-16 13:29 ` Jungseok Lee
2015-07-16 13:29 ` Jungseok Lee
2015-07-16 13:54 ` Jungseok Lee
2015-07-16 13:54 ` Jungseok Lee
2015-07-16 14:24 ` Steven Rostedt
2015-07-16 14:24 ` Steven Rostedt
2015-07-16 15:01 ` Jungseok Lee
2015-07-16 15:01 ` Jungseok Lee
2015-07-16 15:31 ` Steven Rostedt
2015-07-16 15:31 ` Steven Rostedt
2015-07-16 15:52 ` Jungseok Lee
2015-07-16 15:52 ` Jungseok Lee
2015-07-16 20:22 ` Steven Rostedt
2015-07-16 20:22 ` Steven Rostedt
2015-07-17 2:49 ` AKASHI Takahiro
2015-07-17 2:49 ` AKASHI Takahiro
2015-07-17 3:21 ` Steven Rostedt [this message]
2015-07-17 3:21 ` Steven Rostedt
2015-07-16 16:16 ` Steven Rostedt
2015-07-16 16:16 ` Steven Rostedt
2015-07-17 12:40 ` Mark Rutland
2015-07-17 12:40 ` Mark Rutland
2015-07-17 12:51 ` Steven Rostedt
2015-07-17 12:51 ` Steven Rostedt
2015-07-17 13:00 ` Steven Rostedt
2015-07-17 13:00 ` Steven Rostedt
2015-07-17 14:28 ` Jungseok Lee
2015-07-17 14:28 ` Jungseok Lee
2015-07-17 14:41 ` Steven Rostedt
2015-07-17 14:41 ` Steven Rostedt
2015-07-17 14:59 ` Jungseok Lee
2015-07-17 14:59 ` Jungseok Lee
2015-07-17 15:34 ` Jungseok Lee
2015-07-17 15:34 ` Jungseok Lee
2015-07-17 16:01 ` Steven Rostedt
2015-07-17 16:01 ` Steven Rostedt
2015-07-20 16:20 ` Will Deacon
2015-07-20 16:20 ` Will Deacon
2015-07-20 23:53 ` AKASHI Takahiro
2015-07-20 23:53 ` AKASHI Takahiro
2015-07-21 10:26 ` AKASHI Takahiro
2015-07-21 10:26 ` AKASHI Takahiro
2015-07-21 14:34 ` Jungseok Lee
2015-07-21 14:34 ` Jungseok Lee
2015-08-03 9:09 ` Will Deacon
2015-08-03 9:09 ` Will Deacon
2015-08-03 14:01 ` Steven Rostedt
2015-08-03 14:01 ` Steven Rostedt
2015-08-03 14:04 ` Will Deacon
2015-08-03 14:04 ` Will Deacon
2015-08-03 16:30 ` Jungseok Lee
2015-08-03 16:30 ` Jungseok Lee
2015-08-03 16:57 ` Steven Rostedt
2015-08-03 16:57 ` Steven Rostedt
2015-08-03 17:22 ` Jungseok Lee
2015-08-03 17:22 ` Jungseok Lee
2015-08-03 17:32 ` Steven Rostedt
2015-08-03 17:32 ` Steven Rostedt
2015-08-04 7:41 ` AKASHI Takahiro
2015-08-04 7:41 ` AKASHI Takahiro
2015-07-17 2:04 ` AKASHI Takahiro
2015-07-17 2:04 ` AKASHI Takahiro
2015-07-17 14:38 ` Jungseok Lee
2015-07-17 14:38 ` Jungseok Lee
2015-07-16 14:28 ` Mark Rutland
2015-07-16 14:28 ` Mark Rutland
2015-07-16 14:34 ` Steven Rostedt
2015-07-16 14:34 ` Steven Rostedt
2015-07-17 2:09 ` AKASHI Takahiro
2015-07-17 2:09 ` AKASHI Takahiro
2015-07-13 5:29 ` [RFC 3/3] arm64: ftrace: mcount() should not create a stack frame AKASHI Takahiro
2015-07-13 5:29 ` AKASHI Takahiro
2015-07-13 15:01 ` [RFC 0/3] arm64: ftrace: fix incorrect output from stack tracer Jungseok Lee
2015-07-13 15:01 ` Jungseok Lee
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