linux-kernel - Re: [PATCH v1 -next 10/11] cgroup/cpuset: guard cpuset-v1 code under CONFIG_CPUSETS

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Message-ID: <bcbaeb36-ad90-47a0-b832-86eadefd3e6a@huaweicloud.com>
Date: Mon, 26 Aug 2024 09:34:58 +0800
From: Chen Ridong <chenridong@...weicloud.com>
To: Waiman Long <longman@...hat.com>, tj@...nel.org, lizefan.x@...edance.com,
 hannes@...xchg.org, mkoutny@...e.com
Cc: cgroups@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 -next 10/11] cgroup/cpuset: guard cpuset-v1 code under
 CONFIG_CPUSETS_V1



On 2024/8/26 1:25, Waiman Long wrote:
> On 8/23/24 06:01, Chen Ridong wrote:
>> This patch introduces CONFIG_CPUSETS_V1 and guard cpuset-v1 code under
>> CONFIG_CPUSETS_V1. The default value of CONFIG_CPUSETS_V1 is N, so that
>> user who adopted v2 don't have 'pay' for cpuset v1.
>> Besides, to make code succinct, rename '__cpuset_memory_pressure_bump()'
>> to 'cpuset_memory_pressure_bump()', and expose it to the world, which
>> takes place of the old mocro 'cpuset_memory_pressure_bump'.
>>
>> Signed-off-by: Chen Ridong <chenridong@...wei.com>
>> ---
>>   include/linux/cpuset.h          |  8 +-------
>>   init/Kconfig                    | 13 +++++++++++++
>>   kernel/cgroup/Makefile          |  3 ++-
>>   kernel/cgroup/cpuset-internal.h | 15 +++++++++++++++
>>   kernel/cgroup/cpuset-v1.c       | 10 ++++++----
>>   kernel/cgroup/cpuset.c          |  2 ++
>>   6 files changed, 39 insertions(+), 12 deletions(-)
>>
>> diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
>> index 2a6981eeebf8..f91f1f61f482 100644
>> --- a/include/linux/cpuset.h
>> +++ b/include/linux/cpuset.h
>> @@ -99,13 +99,7 @@ static inline bool cpuset_zone_allowed(struct zone 
>> *z, gfp_t gfp_mask)
>>   extern int cpuset_mems_allowed_intersects(const struct task_struct 
>> *tsk1,
>>                         const struct task_struct *tsk2);
>> -#define cpuset_memory_pressure_bump()                 \
>> -    do {                            \
>> -        if (cpuset_memory_pressure_enabled)        \
>> -            __cpuset_memory_pressure_bump();    \
>> -    } while (0)
>> -extern int cpuset_memory_pressure_enabled;
>> -extern void __cpuset_memory_pressure_bump(void);
>> +extern void cpuset_memory_pressure_bump(void);
>>   extern void cpuset_task_status_allowed(struct seq_file *m,
>>                       struct task_struct *task);
> 
> As you are introducing a new CONFIG_CPUSET_V1 kconfig option, you can 
> use it to eliminate a useless function call if cgroup v1 isn't enabled. 
> Not just this function, all the v1 specific functions should have a 
> !CONFIG_CPUSET_V1 version that can be optimized out.
> 
> Cheers,
> Longman
> 
> 
Hi, Longman, currently, we have only added one place to manage all the 
functions whose are empty if !CONFIG_CPUSET_V1 is not defined , and the 
caller does not need to care about using cpuset v1 or v2, which makes it 
succinct.

However, we have to add !CONFIG_CPUSET_V1 to many places to avoid 
useless function calls. I am not opposed to do this if you thick it 'a 
better implementation.

Thanks,
Ridong