linux-kernel - Re: [PATCH v4 1/2] nohz: add tick_nohz_full_cpumask_or() and

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Message-ID: <5526B5C6.6010202@ezchip.com>
Date:	Thu, 9 Apr 2015 13:24:22 -0400
From:	Chris Metcalf <cmetcalf@...hip.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	Frederic Weisbecker <fweisbec@...il.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Ingo Molnar <mingo@...hat.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/2] nohz: add tick_nohz_full_cpumask_or() and _andnot()
 APIs

On 04/09/2015 01:07 PM, Peter Zijlstra wrote:
> On Thu, Apr 09, 2015 at 01:00:38PM -0400, Chris Metcalf wrote:
>> +static inline void tick_nohz_full_cpumask_or(struct cpumask *mask)
> This still reads as if you're doing: nohz_full_mask |= mask.
>
> I think the suggestion done by Frederic is the right one, reverse the
> lot, have:
>
> 	isolcpu_map_or(nohz_full_map) := isolcpus_map |= nohz_full_map
>
> Or just completely give up and just write readable code under an #ifdef.

OK, so let's go with v5 (in the other thread) plus comments on init 
ordering, then.
I'll repost that shortly.

However, I'd still appreciate guidance on the naming, since I do
have a patch outstanding to fiddle with cpumasks for nohz_full
(in the other case, for the tilegx network driver irq mask).

So here's the obvious readable code snippet approach:

#ifdef CONFIG_NO_HZ_FULL
         cpumask_or(some_random_map, some_random_map, tick_nohz_full_map);
#endif

Some possible names so we can macroize them to no-ops:

         exclude_nohz_full_cpus_from(some_random_map);
or
         remove_nohz_full_cpus_from(some_random_map);

         include_nohz_full_cpus_in(some_random_map);
or
         add_nohz_full_cpus_to(some_random_map);

or perhaps with better namespace prefixes, but more confusing to read:

         tick_nohz_full_exclude_cpus_from(some_random_map);
or
         tick_nohz_full_remove_cpus_from(some_random_map);

         tick_nohz_full_include_cpus_in(some_random_map);
or
         tick_nohz_full_add_cpus_to(some_random_map);

Any of these sound good? Any other ideas?

-- 
Chris Metcalf, EZChip Semiconductor
http://www.ezchip.com

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