From: Michael Ellerman <mpe@ellerman•id.au>
To: Frank Rowand <frowand.list@gmail•com>,
Tyrel Datwyler <turtle.in.the.kernel@gmail•com>,
Tyrel Datwyler <tyreld@linux•vnet.ibm.com>,
robh+dt@kernel•org
Cc: linuxppc-dev@lists•ozlabs.org, linux-kernel@vger•kernel.org,
devicetree@vger•kernel.org, nfont@linux•vnet.ibm.com,
rostedt@goodmis•org, mingo@redhat•com
Subject: Re: [PATCH] of: introduce event tracepoints for dynamic device_node lifecyle
Date: Fri, 21 Apr 2017 11:57:19 +1000 [thread overview]
Message-ID: <87vapyttds.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <58F90D56.9070602@gmail.com>
Frank Rowand <frowand.list@gmail•com> writes:
> On 04/20/17 09:51, Tyrel Datwyler wrote:
>> On 04/19/2017 09:43 PM, Frank Rowand wrote:
...
>>> Which ends up being this code:
>>>
>>> of_platform_default_populate_init()
>>> of_platform_default_populate()
>>> of_platform_populate()
>>> [[ of_find_node_by_path("/") ]]
>>> [[ of_find_node_opts_by_path(path, NULL) ]]
>>> of_node_get(of_root)
>>>
>>> Note that some functions can be left out of the ARM call stack, with
>>> a return going back more than one level. The functions in the call
>>> list above that are enclosed in '[[' and ']]' were found by source
>>> inspection in those cases.
>>
>> The same thing is encountered in ppc64 stack traces. I assume it is
>> generally inlining of small functions, but I've never actually verified
>> that theory. Probably should take the time to investigate, or just ask
>> someone.
>
> Yes, inlining small functions is one reason for this.
>
> Another case I often find is that when function A calls function B calls
> function C. If the final statement of function B is 'return C()' then
> there is no need for function C to return through function B, it can
> instead return directly to function A.
It's called "Tail call optimisation", and that's more or less a good
description.
cheers
next prev parent reply other threads:[~2017-04-21 1:57 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-18 0:32 [PATCH] of: introduce event tracepoints for dynamic device_node lifecyle Tyrel Datwyler
2017-04-18 0:35 ` Tyrel Datwyler
2017-04-18 16:46 ` Rob Herring
2017-04-19 2:30 ` Oliver O'Halloran
2017-04-19 10:13 ` Michael Ellerman
2017-04-19 21:13 ` Tyrel Datwyler
2017-04-19 0:07 ` Frank Rowand
2017-04-19 1:31 ` Michael Ellerman
2017-04-19 2:31 ` Frank Rowand
2017-04-19 18:33 ` Tyrel Datwyler
2017-04-19 23:27 ` Tyrel Datwyler
2017-04-20 2:33 ` Steven Rostedt
2017-04-20 4:47 ` Frank Rowand
2017-04-20 5:24 ` Tyrel Datwyler
2017-04-20 13:37 ` Steven Rostedt
2017-04-20 4:43 ` Frank Rowand
2017-04-20 5:13 ` Frank Rowand
2017-04-20 16:51 ` Tyrel Datwyler
2017-04-20 19:34 ` Frank Rowand
2017-04-21 1:57 ` Michael Ellerman [this message]
2017-04-19 1:42 ` Frank Rowand
2017-04-19 2:49 ` Steven Rostedt
2017-04-19 18:45 ` Tyrel Datwyler
2017-04-20 2:37 ` Frank Rowand
2017-04-20 10:44 ` Frank Rowand
2017-04-19 2:46 ` Steven Rostedt
2017-04-19 3:12 ` Frank Rowand
2017-04-19 17:44 ` Frank Rowand
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