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From:   Atish Patra <Atish.Patra@wdc.com>
To:     Palmer Dabbelt <palmer@sifive.com>,
        "anup@brainfault.org" <anup@brainfault.org>,
        Paul Walmsley <paul.walmsley@sifive.com>
CC:     Anup Patel <Anup.Patel@wdc.com>,
        "aou@eecs.berkeley.edu" <aou@eecs.berkeley.edu>,
        Christoph Hellwig <hch@infradead.org>,
        "linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] RISC-V: defconfig: Enable NO_HZ_IDLE and HIGH_RES_TIMERS
Thread-Topic: [PATCH] RISC-V: defconfig: Enable NO_HZ_IDLE and HIGH_RES_TIMERS
Thread-Index: AQHVCue2HEus4pRvEEGYJRX3qv0JO6Zzr7wAgA01ZYCAAB9GgA==
Date:   Tue, 28 May 2019 19:39:48 +0000
Message-ID: <D5957468-5A82-46FA-9D12-A35CF59C7DED@wdc.com>
References: <mhng-2b0ca072-2d6d-4422-96a2-2a4254255cc6@palmer-si-x1e>
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> On 5/28/19 10:47 AM, Palmer Dabbelt wrote:
>> 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:
>>>=20
>>> This patch enables NO_HZ_IDLE (idle dynamic ticks) and HIGH_RES_TIMERS
>>> (hrtimers) in RV32 and RV64 defconfigs.
>>>=20
>>> Both of the above options are enabled by default for architectures
>>> such as x86, ARM, and ARM64.
>>>=20
>>> 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.
>>>=20
>>> This patch is tested on SiFive Unleashed board and QEMU Virt machine.
>>>=20
>>> 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(+)
>>>=20
>>> diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfi=
g
>>> index 2fd3461e50ab..f254c352ec57 100644
>>> --- a/arch/riscv/configs/defconfig
>>> +++ b/arch/riscv/configs/defconfig
>>> @@ -1,5 +1,7 @@
>>>  CONFIG_SYSVIPC=3Dy
>>>  CONFIG_POSIX_MQUEUE=3Dy
>>> +CONFIG_NO_HZ_IDLE=3Dy
>>> +CONFIG_HIGH_RES_TIMERS=3Dy
>>>  CONFIG_IKCONFIG=3Dy
>>>  CONFIG_IKCONFIG_PROC=3Dy
>>>  CONFIG_CGROUPS=3Dy
>>> diff --git a/arch/riscv/configs/rv32_defconfig b/arch/riscv/configs/rv3=
2_defconfig
>>> index 1a911ed8e772..d5449ef805a3 100644
>>> --- a/arch/riscv/configs/rv32_defconfig
>>> +++ b/arch/riscv/configs/rv32_defconfig
>>> @@ -1,5 +1,7 @@
>>>  CONFIG_SYSVIPC=3Dy
>>>  CONFIG_POSIX_MQUEUE=3Dy
>>> +CONFIG_NO_HZ_IDLE=3Dy
>>> +CONFIG_HIGH_RES_TIMERS=3Dy
>>>  CONFIG_IKCONFIG=3Dy
>>>  CONFIG_IKCONFIG_PROC=3Dy
>>>  CONFIG_CGROUPS=3Dy
>>> --
>>> 2.17.1
>>=20
>> Hi All,
>>=20
>> Any comments on this one?
>>=20
>> @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 c=
ausing
> trouble. =20

Are you talking about the trouble with CONFIG_NO_HZ_IDLE we were seeing las=
t 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.


--=20
Regards,
Atish