Hi Samuel, On Thu, Sep 28, 2023 at 5:04 PM Samuel Holland <samuel.holland@xxxxxxxxxx> wrote: > > On 2023-09-28 5:45 AM, Prabhakar wrote: > > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx> > > > > 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. > > This is only true if you have the Sstc extension and can set stimecmp directly. > Otherwise you have the overhead of an SBI call, which is going to be much higher > than an MMIO write. So the rating should depend on Sstc, as in this patch: > > https://lore.kernel.org/linux-riscv/20230710131902.1459180-3-apatel@xxxxxxxxxxxxxxxx/ > Thank you for the pointer. Do you know any tool/util which I can use to make comparisons? Cheers, Prabhakar
