linux-kernel - Re: [PATCH v8 6/7] selftests: Add benchmark for syscall user dispatch

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Date:   Tue, 1 Dec 2020 14:58:23 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Gabriel Krisman Bertazi <krisman@...labora.com>
Cc:     luto@...nel.org, tglx@...utronix.de, gofmanp@...il.com,
        christian.brauner@...ntu.com, peterz@...radead.org,
        willy@...radead.org, shuah@...nel.org,
        linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
        linux-kselftest@...r.kernel.org, x86@...nel.org,
        kernel@...labora.com
Subject: Re: [PATCH v8 6/7] selftests: Add benchmark for syscall user dispatch

On Fri, Nov 27, 2020 at 02:32:37PM -0500, Gabriel Krisman Bertazi wrote:
> This is the patch I'm using to evaluate the impact syscall user dispatch
> has on native syscall (syscalls not redirected to userspace) when
> enabled for the process and submiting syscalls though the unblocked
> dispatch selector. It works by running a step to define a baseline of
> the cost of executing sysinfo, then enabling SUD, and rerunning that
> step.
> 
> On my test machine, an AMD Ryzen 5 1500X, I have the following results
> with the latest version of syscall user dispatch patches.
> 
> root@...a:~# syscall_user_dispatch/sud_benchmark
>   Calibrating test set to last ~5 seconds...
>   test iterations = 37500000
>   Avg syscall time 134ns.
>   Caught sys_ff00
>   trapped_call_count 1, native_call_count 0.
>   Avg syscall time 147ns.
>   Interception overhead: 9.7% (+13ns).
> 
> Signed-off-by: Gabriel Krisman Bertazi <krisman@...labora.com>

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook