* Demi Marie Obenour:
> On 1/30/23 02:17, Florian Weimer wrote:
>> * Demi Marie Obenour:
>>
>>> What about the new SFrame unwind info?
>>
>> It has the same limitation as DWARF: there's no mainline kernel
>> implementation for profiling or bpftrace.
>>
>> Thanks,
>> Florian
>
> Have you
On 1/30/23 02:17, Florian Weimer wrote:
> * Demi Marie Obenour:
>
>> What about the new SFrame unwind info?
>
> It has the same limitation as DWARF: there's no mainline kernel
> implementation for profiling or bpftrace.
>
> Thanks,
> Florian
Have you considered writing such an implementation,
* Demi Marie Obenour:
> What about the new SFrame unwind info?
It has the same limitation as DWARF: there's no mainline kernel
implementation for profiling or bpftrace.
Thanks,
Florian
___
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To
Daan De Meyer via devel wrote:
>> What about the new SFrame unwind info?
>
> We're closely following up on this new format and will compare it against
> frame pointers if a patch introducing a kernel unwinder for sframe is
> proposed and likely to be merged. It's still very early days for SFrame
hat happens first.
Cheers,
Daan
From: Demi Marie Obenour
Sent: 16 January 2023 20:33
To: devel@lists.fedoraproject.org
Subject: Re: -fno-omit-frame-pointer does not work as adverti
On 1/16/23 08:40, Florian Weimer wrote:
> * Daniel Alley:
>
>> What has happened is that because -O2 optimized away all of the stack
>> access for the function, so it uses no space on the stack, so there is
>> no stack frame separate from the caller's.
>>
>> It is unlikely that the critical
* Daniel Alley:
> What has happened is that because -O2 optimized away all of the stack
> access for the function, so it uses no space on the stack, so there is
> no stack frame separate from the caller's.
>
> It is unlikely that the critical bottleneck of any applications will
> be on such a
On 1/15/23 12:58, Kevin Kofler via devel wrote:
> Daniel Alley wrote:
>> The quotation says the opposite of what you are saying. "leaves the frame
>> pointer pointing to the caller's frame" => the caller set the frame
>> pointer, the leaf did not, therefore the leaf function will not show up
>>
* Kevin Kofler via devel:
> Hi,
>
> to those who are pushing the -fno-omit-frame-pointer change: Are you aware
> that neither that flag nor even -mno-omit-leaf-frame-pointer actually
> guarantee that every leaf function is going to carry a frame pointer, as
> required for your backtraces?
Daniel Alley wrote:
> The quotation says the opposite of what you are saying. "leaves the frame
> pointer pointing to the caller's frame" => the caller set the frame
> pointer, the leaf did not, therefore the leaf function will not show up
> but the caller still will.
No, that is not what it
> Daniel Alley wrote:
>
> But it can be in the function CALLING such a function, and said function
> will be completely missing from the backtrace.
>
> Quoting your link
> [https://developer.arm.com/documentation/dui0774/k/Compiler-Command-line-O...]:
The quotation says the opposite of what
Daniel Alley wrote:
> It is unlikely that the critical bottleneck of any applications will be on
> such a function.
But it can be in the function CALLING such a function, and said function
will be completely missing from the backtrace.
Quoting your link
On Sun, 15 Jan 2023 at 03:33, Daniel Alley wrote:
> > Hi,
> >
>
> > Frame pointers sound like a simple solution to unwinding, but they are
> not.
> > They are no complete replacement for unwinding information.
> >
> > Kevin Kofler
>
> I don't think anyone ever argued that frame pointers
> Hi,
>
> to those who are pushing the -fno-omit-frame-pointer change: Are you aware
> that neither that flag nor even -mno-omit-leaf-frame-pointer actually
> guarantee that every leaf function is going to carry a frame pointer, as
> required for your backtraces?
This feels slightly too
Hi,
to those who are pushing the -fno-omit-frame-pointer change: Are you aware
that neither that flag nor even -mno-omit-leaf-frame-pointer actually
guarantee that every leaf function is going to carry a frame pointer, as
required for your backtraces?
See for yourself:
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