linux-kernel - Re: [PATCH] RISC-V: defconfig: Enable NO_HZ_IDLE and HIGH_RES

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Date:   Tue, 28 May 2019 19:39:48 +0000
From:   Atish Patra <Atish.Patra@....com>
To:     Palmer Dabbelt <palmer@...ive.com>,
        "anup@...infault.org" <anup@...infault.org>,
        Paul Walmsley <paul.walmsley@...ive.com>
CC:     Anup Patel <Anup.Patel@....com>,
        "aou@...s.berkeley.edu" <aou@...s.berkeley.edu>,
        Christoph Hellwig <hch@...radead.org>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] RISC-V: defconfig: Enable NO_HZ_IDLE and HIGH_RES_TIMERS

> On 5/28/19 10:47 AM, Palmer Dabbelt wrote:
>> On Mon, 20 May 2019 01:05:22 PDT (-0700), anup@...infault.org wrote:
>>> On Wed, May 15, 2019 at 12:00 PM Anup Patel <Anup.Patel@....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@....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.  

Are you talking about the trouble with CONFIG_NO_HZ_IDLE we were seeing last year or something else ?

CONFIG_NO_HZ_IDLE was well tested and fixed last year.

I'm in the process of switching to Yocto right now for my tests, so
> it'll be a bit slow.


-- 
Regards,
Atish