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Message-ID: <537ac244-74b2-42ad-97a7-475ec27f2134@bytedance.com>
Date: Mon, 22 Apr 2024 16:04:03 +0800
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Subject: Re: Re: [PATCH v2 1/4] virtio_balloon: separate vm events into a
 function
To: David Hildenbrand <david@redhat.com>, linux-kernel@vger.kernel.org,
 linux-mm@kvack.org, virtualization@lists.linux.dev
Cc: mst@redhat.com, jasowang@redhat.com, xuanzhuo@linux.alibaba.com,
 akpm@linux-foundation.org
References: <20240422074254.1440457-1-pizhenwei@bytedance.com>
 <20240422074254.1440457-2-pizhenwei@bytedance.com>
 <6a182645-1f7f-4b7d-a16a-36e9b1684c58@redhat.com>
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From: zhenwei pi <pizhenwei@bytedance.com>
In-Reply-To: <6a182645-1f7f-4b7d-a16a-36e9b1684c58@redhat.com>
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On 4/22/24 15:47, David Hildenbrand wrote:
> On 22.04.24 09:42, zhenwei pi wrote:
>> All the VM events related statistics have dependence on
>> 'CONFIG_VM_EVENT_COUNTERS', once any stack variable is required by any
>> VM events in future, we would have codes like:
>>   #ifdef CONFIG_VM_EVENT_COUNTERS
>>        unsigned long foo;
>>   #endif
>>        ...
>>   #ifdef CONFIG_VM_EVENT_COUNTERS
>>        foo = events[XXX] + events[YYY];
>>        update_stat(vb, idx++, VIRTIO_BALLOON_S_XXX, foo);
>>   #endif
>>
>> Separate vm events into a single function, also remove
> 
> Why not simply use __maybe_unused for that variable?
> 

1>
static unsigned int update_balloon_stats()
{
     unsigned __maybe_unused long foo;

     ...
#ifdef CONFIG_VM_EVENT_COUNTERS
     foo = events[XXX] + events[YYY];
     update_stat(vb, idx++, VIRTIO_BALLOON_S_XXX, foo);
#endif
}

2>
static inline unsigned int update_balloon_vm_stats()
{
#ifdef CONFIG_VM_EVENT_COUNTERS
     unsigned long foo;

     foo = events[XXX] + events[YYY];
     update_stat(vb, idx++, VIRTIO_BALLOON_S_XXX, foo);
#endif
}

 From the point of my view, I don't need to compile code in my brain 
when reading codes for case 2. :)

-- 
zhenwei pi