Messages in this thread | | | Date | Thu, 29 Mar 2018 14:07:52 -0400 | From | Steven Rostedt <> | Subject | Re: [RFC PATCH for 4.17 02/21] rseq: Introduce restartable sequences system call (v12) |
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On Thu, 29 Mar 2018 14:02:33 -0400 (EDT) Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
> Currently, anyone using ptrace on a process has pretty much given up all > hopes of performance. Processes will use rseq to gain performance, not the > opposite, so this deterioration will be unwelcome.
The ptrace path has nothing to do with ptrace anymore, and probably be hard to notice the performance hit. You simply set a TIF flag, and on exit of the syscall it jumps to a path that checks special cases (tracing system calls being one of them). It's called the ptrace path because ptrace was the first one to use it (I'm guessing, I haven't actually looked at the history).
This is used to add any system call checks that are not done during normal operation. And this certainly falls under that category.
-- Steve
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