linux-kernel - Re: [PATCH v2 4/6] debugobjects: Don't start fill if there are remaining nodes locally

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Message-ID: <263b875c-7485-1331-fec5-ff492a295d62@huawei.com>
Date: Wed, 11 Sep 2024 09:21:24 +0800
From: "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>
To: Thomas Gleixner <tglx@...utronix.de>, Andrew Morton
	<akpm@...ux-foundation.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 4/6] debugobjects: Don't start fill if there are
 remaining nodes locally



On 2024/9/10 23:29, Leizhen (ThunderTown) wrote:
> 
> 
> On 2024/9/9 21:51, Leizhen (ThunderTown) wrote:
>> +static void fill_pool(void)
>> +{
>> +	gfp_t gfp = __GFP_HIGH | __GFP_NOWARN;
>> +	static atomic_t cpus_allocating;
>>  
>>  	if (unlikely(!obj_cache))
>>  		return;
>>  
>> +	/*
>> +	 * Avoid allocation and lock contention when
>> +	 *
>> +	 *   - the CPU local pool has at least 2 objects left
>> +	 *   - another CPU is already in the allocation path
>> +	 *   - the global pool has not reached the critical level yet
>> +	 */
>> +	if (this_cpu_read(percpu_obj_pool.obj_free) > 1 && atomic_read(&cpus_allocating) &&
> 
> I rethink that 'cpus_allocating' and 'percpu_obj_pool.obj_free > 1' should be
> contradictory. We can only choose one of them. If 'cpus_allocating' can work,
> there's no need for another. Since I had no way to prove that 'cpus_allocating'

Sorry, I mistyped in a hurry yesterday, and it's 'percpu_obj_pool.obj_free > 1'
that should be deleted.


> would work, I removed it in V3.
> 
>> +	    READ_ONCE(obj_pool_free) > (debug_objects_pool_min_level / 2))
>> +		return;
>> +
>> +	atomic_inc(&cpus_allocating);
>>  	while (READ_ONCE(obj_pool_free) < debug_objects_pool_min_level) {
>>  		struct debug_obj *new[ODEBUG_BATCH_SIZE];
>>  		int cnt;
> 

-- 
Regards,
  Zhen Lei