linux-kernel - Re: [PATCH 0/3] fgraph: Do not save calltime in shadow stack

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Message-Id: <20240915142233.168da2dcd06000dc86a34a1e@kernel.org>
Date: Sun, 15 Sep 2024 14:22:33 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org, Masami
 Hiramatsu <mhiramat@...nel.org>, Mark Rutland <mark.rutland@....com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, Andrew Morton
 <akpm@...ux-foundation.org>, Jiri Olsa <olsajiri@...il.com>
Subject: Re: [PATCH 0/3] fgraph: Do not save calltime in shadow stack

On Sat, 14 Sep 2024 17:48:05 -0400
Steven Rostedt <rostedt@...dmis.org> wrote:

> 
> Now that there's more users of the function graph infrastructure, the
> calltime field on the shadow stack wastes space and also getting the
> timestamp is a waste of time for those that do not use it.
> 
> Instead, have the only two users of it (function graph tracer and the
> profiler) store it in its own shadow stack variable.

This series looks good to me. Instead of adding add-hoc flag, this
solves call-time clearer.

For this series,

Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>

Thank you,

> 
> Steven Rostedt (3):
>       fgraph: Use fgraph data to store subtime for profiler
>       ftrace: Use a running sleeptime instead of saving in shadow stack
>       ftrace: Have calltime be saved in the fgraph storage
> 
> ----
>  include/linux/ftrace.h               |  5 +--
>  include/linux/sched.h                |  1 +
>  kernel/trace/fgraph.c                | 85 +++++++++++++++++++++---------------
>  kernel/trace/ftrace.c                | 45 +++++++++++++------
>  kernel/trace/trace.h                 |  1 +
>  kernel/trace/trace_functions_graph.c | 52 +++++++++++++++++++++-
>  6 files changed, 137 insertions(+), 52 deletions(-)


-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>