linux-kernel - Re: [PATCH] clocksource/drivers/riscv: Increase the clock

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Date:   Thu, 28 Sep 2023 13:42:15 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Prabhakar <prabhakar.csengg@...il.com>
Cc:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Samuel Holland <samuel@...lland.org>,
        Anup Patel <anup@...infault.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Biju Das <biju.das.jz@...renesas.com>,
        linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-renesas-soc@...r.kernel.org,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH] clocksource/drivers/riscv: Increase the clock_event rating

On Thu, Sep 28, 2023 at 12:45 PM Prabhakar <prabhakar.csengg@...il.com> wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
>
> Renesas RZ/Five SoC has OSTM blocks which can be used for clock_event and
> clocksource [0]. The clock_event rating for the OSTM is set 300 but
> whereas the rating for riscv-timer clock_event is set to 100 due to which
> the kernel is choosing OSTM for clock_event.
>
> As riscv-timer is much more efficient than MMIO clock_event, increase the
> rating to 400 so that the kernel prefers riscv-timer over the MMIO based
> clock_event.
>
> [0] drivers/clocksource/renesas-ostm.c
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> ---
> Note, Ive set the rating similar to RISC-V clocksource, on ARM architecture
> the rating for clk_event is set to 450.

Makes sense.
Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds