Re: [PATCH 1/3] trace/syslog: seperate cold paths of tracing functions

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Sun, Jun 01, 2025 at 06:12:29PM +0000, Tanish Desai wrote:
> inline: move hot paths from .c to .h for better performance
> Moved frequently used hot paths from the .c file to the .h file to enable inlining
> and improve performance. This approach is inspired by past QEMU optimizations,
> where performance-critical code was inlined based on profiling results.
> 
> Signed-off-by: Tanish Desai <tanishdesai37@gmail.com>
> ---
>  scripts/tracetool/backend/syslog.py | 36 +++++++++++++++++++++++------
>  1 file changed, 29 insertions(+), 7 deletions(-)

This commit description doesn't match what the patch does.

What is the purpose of creating a _syslog_trace_foo() function in the .c
file instead of calling syslog() directly from the .h file?

> 
> diff --git a/scripts/tracetool/backend/syslog.py b/scripts/tracetool/backend/syslog.py
> index 012970f6cc..52b8ff65ea 100644
> --- a/scripts/tracetool/backend/syslog.py
> +++ b/scripts/tracetool/backend/syslog.py
> @@ -21,8 +21,12 @@
>  
>  
>  def generate_h_begin(events, group):
> -    out('#include <syslog.h>',
> -        '')
> +    out('#include <syslog.h>')
> +    for event in events:
> +        out('void _syslog_%(api)s(%(args)s);',
> +            api=event.api(),
> +            args=event.args)
> +    out('')
>  
>  
>  def generate_h(event, group):
> @@ -37,17 +41,35 @@ def generate_h(event, group):
>          cond = "trace_event_get_state(%s)" % ("TRACE_" + event.name.upper())
>  
>      out('    if (%(cond)s) {',
> -        '#line %(event_lineno)d "%(event_filename)s"',
> -        '        syslog(LOG_INFO, "%(name)s " %(fmt)s %(argnames)s);',
> -        '#line %(out_next_lineno)d "%(out_filename)s"',
> +            '       _syslog_%(api)s(%(args)s);',
>          '    }',
>          cond=cond,
>          event_lineno=event.lineno,
>          event_filename=os.path.relpath(event.filename),
>          name=event.name,
>          fmt=event.fmt.rstrip("\n"),
> -        argnames=argnames)
> -
> +        argnames=argnames,
> +        api=event.api(),
> +        args=", ".join(event.args.names()))
> +
> +
> +def generate_c(event, group):
> +        argnames = ", ".join(event.args.names())
> +        if len(event.args) > 0:
> +            argnames = ", " + argnames
> +        out('void _syslog_%(api)s(%(args)s){',
> +        '   #line %(event_lineno)d "%(event_filename)s"',
> +        '            syslog(LOG_INFO, "%(name)s " %(fmt)s %(argnames)s);',
> +        '   #line %(out_next_lineno)d "%(out_filename)s"',
> +        '}',
> +        '',
> +        event_lineno=event.lineno,
> +        event_filename=os.path.relpath(event.filename),
> +        name=event.name,
> +        fmt=event.fmt.rstrip("\n"),
> +        argnames=argnames,
> +        api=event.api(),
> +        args=event.args)    
>  
>  def generate_h_backend_dstate(event, group):
>      out('    trace_event_get_state_dynamic_by_id(%(event_id)s) || \\',
> -- 
> 2.34.1
> 

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