Re: [PATCH v7 0/8] x86/module: use large ROX pages for text allocations

Steven Rostedt
2024-11-18T18:24:39Z

On Wed, 23 Oct 2024 19:27:03 +0300
Mike Rapoport <rppt@kernel.org> wrote:

> From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
>
> Hi,
>
> This is an updated version of execmem ROX caches.
>

FYI, I booted a kernel before and after applying these patches with my
change:

https://lore.kernel.org/20241017113105.1edfa943@gandalf.local.home

Before these patches:

# cat /sys/kernel/tracing/dyn_ftrace_total_info
57695 pages:231 groups: 9
ftrace boot update time = 14733459 (ns)
ftrace module total update time = 449016 (ns)

After:

# cat /sys/kernel/tracing/dyn_ftrace_total_info
57708 pages:231 groups: 9
ftrace boot update time = 47195374 (ns)
ftrace module total update time = 592080 (ns)

Which caused boot time to slowdown by over 30ms. That may not seem like
much, but we are very concerned about boot time and are fighting every ms
we can get.

-- Steve