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From: Thomas Gleixner <tglx@linutronix.de>
To: James Morse <james.morse@arm.com>, x86@kernel.org,
 linux-kernel@vger.kernel.org
Cc: Fenghua Yu <fenghua.yu@intel.com>, Reinette Chatre
 <reinette.chatre@intel.com>, Ingo Molnar <mingo@redhat.com>, Borislav
 Petkov <bp@alien8.de>, H Peter Anvin <hpa@zytor.com>, Babu Moger
 <Babu.Moger@amd.com>, James Morse <james.morse@arm.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, baolin.wang@linux.alibaba.com, Jamie Iles
 <quic_jiles@quicinc.com>, Xin Hao <xhao@linux.alibaba.com>,
 peternewman@google.com, dfustini@baylibre.com, amitsinght@marvell.com,
 Frederic Weisbecker <frederic@kernel.org>
Subject: Re: [PATCH v8 01/24] tick/nohz: Move tick_nohz_full_mask
 declaration outside the #ifdef
In-Reply-To: <20231215174343.13872-2-james.morse@arm.com>
References: <20231215174343.13872-1-james.morse@arm.com>
 <20231215174343.13872-2-james.morse@arm.com>
Date: Fri, 15 Dec 2023 21:31:42 +0100
Message-ID: <874jgjmclt.ffs@tglx>
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On Fri, Dec 15 2023 at 17:43, 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.

I can pick that up separately, but I'm fine when it goes with the
resctrl lot. For that case:

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>