From: Steven Rostedt <rostedt@goodmis.org>
To: Chengming Zhou <zhouchengming@bytedance.com>
Cc: mingo@redhat.com, catalin.marinas@arm.com, will@kernel.org,
mark.rutland@arm.com, broonie@kernel.org,
songmuchun@bytedance.com, qirui.001@bytedance.com,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64/ftrace: Make function graph use ftrace directly
Date: Tue, 22 Feb 2022 10:52:18 -0500 [thread overview]
Message-ID: <20220222105218.28e3d5aa@gandalf.local.home> (raw)
In-Reply-To: <20220222130049.81284-1-zhouchengming@bytedance.com>
On Tue, 22 Feb 2022 21:00:49 +0800
Chengming Zhou <zhouchengming@bytedance.com> wrote:
> As we do in commit 0c0593b45c9b ("x86/ftrace: Make function graph
> use ftrace directly"), we don't need special hook for graph tracer,
> but instead we use graph_ops:func function to install return_hooker.
>
> Since commit 3b23e4991fb6 ("arm64: implement ftrace with regs") add
> implementation for FTRACE_WITH_REGS on arm64, we can easily adopt
> the same optimization on arm64.
Note. Ideally we want it to hook with DYNAMIC_FTARCE_WITH_ARGS, and not
FTRACE_WITH_REGS. If arm64 is like x86_64, saving all regs at every
function call has a bit more overhead than saving the minimum. The
DYNAMIC_FTRACE_WITH_ARGS, means that the minimum is still saved, but now
exposes the arguments and the stack pointer, which function_graph_tracer
needs.
-- Steve
>
> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
> ---
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next prev parent reply other threads:[~2022-02-22 15:59 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-22 13:00 [PATCH] arm64/ftrace: Make function graph use ftrace directly Chengming Zhou
2022-02-22 15:52 ` Steven Rostedt [this message]
2022-02-22 16:07 ` Mark Rutland
2022-02-23 8:00 ` [External] " Chengming Zhou
2022-02-24 1:30 ` Steven Rostedt
2022-02-24 2:03 ` Chengming Zhou
2022-02-22 15:54 ` Mark Rutland
2022-02-22 16:05 ` Steven Rostedt
2022-02-23 7:55 ` [External] " Chengming Zhou
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