On Mon, Apr 1, 2019 at 6:45 AM Steven Rostedt [off-list ref] wrote:

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

At Linux Plumbers, Andy Lutomirski approached me and pointed out that the
function call syscall_get_arguments() implemented in x86 was horribly
written and not optimized for the standard case of passing in 0 and 6 for
the starting index and the number of system calls to get. When looking at
all the users of this function, I discovered that all instances pass in only
0 and 6 for these arguments. Instead of having this function handle
different cases that are never used, simply rewrite it to return the first 6
arguments of a system call.

This should help out the performance of tracing system calls by ptrace,
ftrace and perf.

[...]

 arch/xtensa/include/asm/syscall.h     | 16 ++----

For xtensa changes:
Acked-by: Max Filippov <jcmvbkbc@gmail.com>

-- 
Thanks.
-- Max