Re: [PATCH v13 RESEND 10/14] arm64: Inline el0_svc_common()

[Linus Walleij]

On Tue, Mar 17, 2026 at 9:20 AM Jinjie Ruan <ruanjinjie@xxxxxxxxxx> wrote:

> After converting arm64 to Generic Entry framework, the compiler no longer
> inlines el0_svc_common() into its caller do_el0_svc(). This introduces
> a small but measurable overhead in the critical system call path.
>
> Manually forcing el0_svc_common() to be inlined restores the
> performance. Benchmarking with perf bench syscall basic on a
> Kunpeng 920 platform (based on v6.19-rc1) shows a ~1% performance
> uplift.
>
> Inlining this function reduces function prologue/epilogue overhead
> and allows for better compiler optimization in the hot system call
> dispatch path.
>
> | Metric     | W/O this patch | With this patch | Change    |
> | ---------- | -------------- | --------------- | --------- |
> | Total time | 2.195 [sec]    | 2.171 [sec]     |  ↓1.1%   |
> | usecs/op   | 0.219575       | 0.217192        |  ↓1.1%   |
> | ops/sec    | 4,554,260      | 4,604,225       |  ↑1.1%    |
>
> Reviewed-by: Kevin Brodsky <kevin.brodsky@xxxxxxx>
> Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>

Reviewed-by: Linus Walleij <linusw@xxxxxxxxxx>

Yours,
Linus Walleij