Re: [PATCH] RISC-V: defconfig: Enable NO_HZ_IDLE and HIGH_RES_TIMERS

[Palmer Dabbelt]

On Mon, 20 May 2019 01:05:22 PDT (-0700), anup@xxxxxxxxxxxxxx wrote:
> On Wed, May 15, 2019 at 12:00 PM Anup Patel <Anup.Patel@xxxxxxx> wrote:
> > This patch enables NO_HZ_IDLE (idle dynamic ticks) and HIGH_RES_TIMERS
> > (hrtimers) in RV32 and RV64 defconfigs.
> >
> > Both of the above options are enabled by default for architectures
> > such as x86, ARM, and ARM64.
> >
> > The idle dynamic ticks helps use save power by stopping timer ticks
> > when the system is idle whereas hrtimers is a much improved timer
> > subsystem compared to the old "timer wheel" based system.
> >
> > This patch is tested on SiFive Unleashed board and QEMU Virt machine.
> >
> > Signed-off-by: Anup Patel <anup.patel@xxxxxxx>
> > ---
> >  arch/riscv/configs/defconfig      | 2 ++
> >  arch/riscv/configs/rv32_defconfig | 2 ++
> >  2 files changed, 4 insertions(+)
> >
> > diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfig
> > index 2fd3461e50ab..f254c352ec57 100644
> > --- a/arch/riscv/configs/defconfig
> > +++ b/arch/riscv/configs/defconfig
> > @@ -1,5 +1,7 @@
> >  CONFIG_SYSVIPC=y
> >  CONFIG_POSIX_MQUEUE=y
> > +CONFIG_NO_HZ_IDLE=y
> > +CONFIG_HIGH_RES_TIMERS=y
> >  CONFIG_IKCONFIG=y
> >  CONFIG_IKCONFIG_PROC=y
> >  CONFIG_CGROUPS=y
> > diff --git a/arch/riscv/configs/rv32_defconfig b/arch/riscv/configs/rv32_defconfig
> > index 1a911ed8e772..d5449ef805a3 100644
> > --- a/arch/riscv/configs/rv32_defconfig
> > +++ b/arch/riscv/configs/rv32_defconfig
> > @@ -1,5 +1,7 @@
> >  CONFIG_SYSVIPC=y
> >  CONFIG_POSIX_MQUEUE=y
> > +CONFIG_NO_HZ_IDLE=y
> > +CONFIG_HIGH_RES_TIMERS=y
> >  CONFIG_IKCONFIG=y
> >  CONFIG_IKCONFIG_PROC=y
> >  CONFIG_CGROUPS=y
> > --
> > 2.17.1
>
> Hi All,
>
> Any comments on this one?
>
> @Palmer, It would be nice to have this in Linux-5.2

My only issue here is testing: IIRC last time we tried this it ended up causing
trouble.  I'm in the process of switching to Yocto right now for my tests, so
it'll be a bit slow.