linux-kernel - Re: [PATCH 1/2] f2fs: add sysfs support for controlling the gc

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Date:	Fri, 02 Aug 2013 09:26:57 +0800
From:	Gu Zheng <guz.fnst@...fujitsu.com>
To:	Namjae Jeon <linkinjeon@...il.com>
CC:	jaegeuk.kim@...sung.com, linux-f2fs-devel@...ts.sourceforge.net,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	Namjae Jeon <namjae.jeon@...sung.com>,
	Pankaj Kumar <pankaj.km@...sung.com>
Subject: Re: [PATCH 1/2] f2fs: add sysfs support for controlling the gc_thread

On 08/02/2013 09:19 AM, Namjae Jeon wrote:

>>>
>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>> index 78777cd..63813be 100644
>>> --- a/fs/f2fs/f2fs.h
>>> +++ b/fs/f2fs/f2fs.h
>>> @@ -430,6 +430,10 @@ struct f2fs_sb_info {
>>>  #endif
>>>  	unsigned int last_victim[2];		/* last victim segment # */
>>>  	spinlock_t stat_lock;			/* lock for stat operations */
>>> +
>>> +	/* For sysfs suppport */
>>> +	struct kobject s_kobj;
>>> +	struct completion s_kobj_unregister;
>>
> Hi. Gu.
>> What is this completion used for? Or it's an ahead design? I do not find
>> synchronization
>> routines use it. Am I missing something?
> You're right. it is my mistake. I will update it on next version patch.
> 
>>
>>
>>>  };
>>>
>>>  /*
>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>>> index 35f9b1a..60d4f67 100644
>>> --- a/fs/f2fs/gc.c
>>> +++ b/fs/f2fs/gc.c
>>> @@ -29,10 +29,11 @@ static struct kmem_cache *winode_slab;
>>>  static int gc_thread_func(void *data)
>>>  {
>>>  	struct f2fs_sb_info *sbi = data;
>>> +	struct f2fs_gc_kthread *gc_th = sbi->gc_thread;
>>>  	wait_queue_head_t *wq = &sbi->gc_thread->gc_wait_queue_head;
>>>  	long wait_ms;
>>>
>>> -	wait_ms = GC_THREAD_MIN_SLEEP_TIME;
>>> +	wait_ms = gc_th->min_sleep_time;
>>>
>>>  	do {
>>>  		if (try_to_freeze())
>>> @@ -45,7 +46,7 @@ static int gc_thread_func(void *data)
>>>  			break;
>>>
>>>  		if (sbi->sb->s_writers.frozen >= SB_FREEZE_WRITE) {
>>> -			wait_ms = GC_THREAD_MAX_SLEEP_TIME;
>>> +			wait_ms = increase_sleep_time(gc_th, wait_ms);
>>>  			continue;
>>>  		}
>>>
>>> @@ -66,15 +67,15 @@ static int gc_thread_func(void *data)
>>>  			continue;
>>>
>>>  		if (!is_idle(sbi)) {
>>> -			wait_ms = increase_sleep_time(wait_ms);
>>> +			wait_ms = increase_sleep_time(gc_th, wait_ms);
>>>  			mutex_unlock(&sbi->gc_mutex);
>>>  			continue;
>>>  		}
>>>
>>>  		if (has_enough_invalid_blocks(sbi))
>>> -			wait_ms = decrease_sleep_time(wait_ms);
>>> +			wait_ms = decrease_sleep_time(gc_th, wait_ms);
>>>  		else
>>> -			wait_ms = increase_sleep_time(wait_ms);
>>> +			wait_ms = increase_sleep_time(gc_th, wait_ms);
>>>
>>>  #ifdef CONFIG_F2FS_STAT_FS
>>>  		sbi->bg_gc++;
>>> @@ -82,7 +83,7 @@ static int gc_thread_func(void *data)
>>>
>>>  		/* if return value is not zero, no victim was selected */
>>>  		if (f2fs_gc(sbi))
>>> -			wait_ms = GC_THREAD_NOGC_SLEEP_TIME;
>>> +			wait_ms = gc_th->no_gc_sleep_time;
>>>  	} while (!kthread_should_stop());
>>>  	return 0;
>>>  }
>>> @@ -101,6 +102,10 @@ int start_gc_thread(struct f2fs_sb_info *sbi)
>>>  		goto out;
>>>  	}
>>>
>>> +	gc_th->min_sleep_time = DEF_GC_THREAD_MIN_SLEEP_TIME;
>>> +	gc_th->max_sleep_time = DEF_GC_THREAD_MAX_SLEEP_TIME;
>>> +	gc_th->no_gc_sleep_time = DEF_GC_THREAD_NOGC_SLEEP_TIME;
>>> +
>>>  	sbi->gc_thread = gc_th;
>>>  	init_waitqueue_head(&sbi->gc_thread->gc_wait_queue_head);
>>>  	sbi->gc_thread->f2fs_gc_task = kthread_run(gc_thread_func, sbi,
>>> diff --git a/fs/f2fs/gc.h b/fs/f2fs/gc.h
>>> index 2c6a6bd..f4bf44c 100644
>>> --- a/fs/f2fs/gc.h
>>> +++ b/fs/f2fs/gc.h
>>> @@ -13,9 +13,9 @@
>>>  						 * whether IO subsystem is idle
>>>  						 * or not
>>>  						 */
>>> -#define GC_THREAD_MIN_SLEEP_TIME	30000	/* milliseconds */
>>> -#define GC_THREAD_MAX_SLEEP_TIME	60000
>>> -#define GC_THREAD_NOGC_SLEEP_TIME	300000	/* wait 5 min */
>>> +#define DEF_GC_THREAD_MIN_SLEEP_TIME	30000	/* milliseconds */
>>> +#define DEF_GC_THREAD_MAX_SLEEP_TIME	60000
>>> +#define DEF_GC_THREAD_NOGC_SLEEP_TIME	300000	/* wait 5 min */
>>>  #define LIMIT_INVALID_BLOCK	40 /* percentage over total user space */
>>>  #define LIMIT_FREE_BLOCK	40 /* percentage over invalid + free space */
>>>
>>> @@ -25,6 +25,11 @@
>>>  struct f2fs_gc_kthread {
>>>  	struct task_struct *f2fs_gc_task;
>>>  	wait_queue_head_t gc_wait_queue_head;
>>> +
>>> +	/* for gc sleep time */
>>> +	unsigned int min_sleep_time;
>>> +	unsigned int max_sleep_time;
>>> +	unsigned int no_gc_sleep_time;
>>
>> Though these attributes are used for gc thread, and in current design
>> gc_thread is always
>> singleton per f2fs_sb, but thare're in fact f2fs sb infos. So I think it's
>> to attach
>> these to f2fs_sb_info. What's your opinion?
> It does not matter wherever it is. but I think that these gc time are
> for gc thread.
> So I put gc time to gc thread.

Yeah, in fact it's also OK. :)

Regards,
Gu

> 
> Thanks for review :)

>>
>> Thanks,
>> Gu
>>
>>>  };
> --
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