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

[Palmer Dabbelt <palmer@sifive.com>]

On Mon, 20 May 2019 01:05:22 PDT (-0700), anup@brainfault.org wrote:
> On Wed, May 15, 2019 at 12:00 PM Anup Patel <Anup.Patel@wdc.com> 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@wdc.com>
>> ---
>>  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.