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Date:   Wed, 9 Aug 2023 15:34:09 -0700
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Subject: Re: [PATCH v5 10/24] tick/nohz: Move tick_nohz_full_mask declaration
 outside the #ifdef
Content-Language: en-US
To:     James Morse <james.morse@arm.com>, <x86@kernel.org>,
        <linux-kernel@vger.kernel.org>
CC:     Fenghua Yu <fenghua.yu@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        H Peter Anvin <hpa@zytor.com>,
        Babu Moger <Babu.Moger@amd.com>,
        <shameerali.kolothum.thodi@huawei.com>,
        D Scott Phillips OS <scott@os.amperecomputing.com>,
        <carl@os.amperecomputing.com>, <lcherian@marvell.com>,
        <bobo.shaobowang@huawei.com>, <tan.shaopeng@fujitsu.com>,
        <xingxin.hx@openanolis.org>, <baolin.wang@linux.alibaba.com>,
        Jamie Iles <quic_jiles@quicinc.com>,
        Xin Hao <xhao@linux.alibaba.com>, <peternewman@google.com>,
        <dfustini@baylibre.com>
References: <20230728164254.27562-1-james.morse@arm.com>
 <20230728164254.27562-11-james.morse@arm.com>
From:   Reinette Chatre <reinette.chatre@intel.com>
In-Reply-To: <20230728164254.27562-11-james.morse@arm.com>
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Hi James,

On 7/28/2023 9:42 AM, James Morse wrote:
> tick_nohz_full_mask lists the CPUs that are nohz_full. This is only
> needed when CONFIG_NO_HZ_FULL is defined. tick_nohz_full_cpu() allows
> a specific CPU to be tested against the mask, and evaluates to false
> when CONFIG_NO_HZ_FULL is not defined.
> 
> The resctrl code needs to pick a CPU to run some work on, a new helper
> prefers housekeeping CPUs by examining the tick_nohz_full_mask. Hiding
> the declaration behind #ifdef CONFIG_NO_HZ_FULL forces all the users to
> be behind an ifdef too.
> 
> Move the tick_nohz_full_mask declaration, this lets callers drop the
> ifdef, and guard access to tick_nohz_full_mask with IS_ENABLED() or
> something like tick_nohz_full_cpu().
> 
> The definition does not need to be moved as any callers should be
> removed at compile time unless CONFIG_NO_HZ_FULL is defined.
> 
> Signed-off-by: James Morse <james.morse@arm.com>
> ---
>  include/linux/tick.h | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)

This is outside of the resctrl area. What is the upstreaming
plan for this patch?

Reinette