linux-kernel - Re: [PATCH bpf-next v3 3/4] x86: implement per-function metadata storage for x86

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Message-ID: <CADxym3ZJf3TEMwCy4JVT1gs9GP=U1n1qss3ycnuMZVyp9TfDdw@mail.gmail.com>
Date: Tue, 4 Mar 2025 10:07:22 +0800
From: Menglong Dong <menglong8.dong@...il.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: peterz@...radead.org, mark.rutland@....com, alexei.starovoitov@...il.com, 
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Subject: Re: [PATCH bpf-next v3 3/4] x86: implement per-function metadata
 storage for x86

On Tue, Mar 4, 2025 at 12:05 AM Steven Rostedt <rostedt@...dmis.org> wrote:
>
> On Mon,  3 Mar 2025 14:53:44 +0800
> Menglong Dong <menglong8.dong@...il.com> wrote:
>
> > In the third case, we make the kernel function 32 bytes aligned, and there
> > will be 32 bytes padding before the functions. According to my testing,
> > the text size didn't increase on this case, which is weird.
> >
> > With 16-bytes padding:
> >
> > -rwxr-xr-x 1 401190688  x86-dev/vmlinux*
> > -rw-r--r-- 1    251068  x86-dev/vmlinux.a
> > -rw-r--r-- 1 851892992  x86-dev/vmlinux.o
> > -rw-r--r-- 1  12395008  x86-dev/arch/x86/boot/bzImage
> >
> > With 32-bytes padding:
> >
> > -rwxr-xr-x 1 401318128 x86-dev/vmlinux*
> > -rw-r--r-- 1    251154 x86-dev/vmlinux.a
> > -rw-r--r-- 1 853636704 x86-dev/vmlinux.o
> > -rw-r--r-- 1  12509696 x86-dev/arch/x86/boot/bzImage
>
> Use the "size" command to see the differences in sizes and not the file size.
>
> $ size vmlinux
>    text    data     bss     dec     hex filename
> 36892658        9798658 16982016        63673332        3cb93f4 vmlinux

Great! It seems that the way I tested has something wrong. I'll
compare the text size with "size" command later.

Thanks!
Menglong Dong

>
> -- Steve