Re: [PATCH 1/7] drivers: base: move mutex lock out of add_memory_section()

Re: [PATCH 1/7] drivers: base: move mutex lock out of add_memory_section()

[Greg Kroah-Hartman]

On Tue, Aug 20, 2013 at 12:24:45PM -0500, Seth Jennings wrote:
> Gah! Forgot the cover letter.

No worries, I barely read them anyway :)

> This patchset just seeks to clean up and refactor some things in
> memory.c for better understanding and possibly better performance due do
> a decrease in mutex acquisitions and refcount churn at boot time.  No
> functional change is intended by this set!

All looks good, thanks for breaking it up into reviewable patches.  Now
applied.

greg k-h

Re: [PATCH 7/7] drivers: base: refactor add_memory_section() to add_memory_block()

[Yasuaki Ishimatsu]

(2013/08/21 2:13), Seth Jennings wrote:
> Right now memory_dev_init() maintains the memory block pointer
> between iterations of add_memory_section().  This is nasty.
> 
> This patch refactors add_memory_section() to become add_memory_block().
> The refactoring pulls the section scanning out of memory_dev_init()
> and simplifies the signature.
> 
> Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
> ---
>   drivers/base/memory.c | 48 +++++++++++++++++++++---------------------------
>   1 file changed, 21 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index 7d9d3bc..021283a 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -602,32 +602,31 @@ static int init_memory_block(struct memory_block **memory,
>   	return ret;
>   }
>   
> -static int add_memory_section(struct mem_section *section,
> -			struct memory_block **mem_p)
> +static int add_memory_block(int base_section_nr)
>   {
> -	struct memory_block *mem = NULL;
> -	int scn_nr = __section_nr(section);
> -	int ret = 0;
> -
> -	if (mem_p && *mem_p) {
> -		if (scn_nr >= (*mem_p)->start_section_nr &&
> -		    scn_nr <= (*mem_p)->end_section_nr) {
> -			mem = *mem_p;
> -		}
> -	}
> +	struct memory_block *mem;
> +	int i, ret, section_count = 0, section_nr;
>   
> -	if (mem)
> -		mem->section_count++;
> -	else {
> -		ret = init_memory_block(&mem, section, MEM_ONLINE);
> -		/* store memory_block pointer for next loop */
> -		if (!ret && mem_p)
> -			*mem_p = mem;
> +	for (i = base_section_nr;
> +	     (i < base_section_nr + sections_per_block) && i < NR_MEM_SECTIONS;
> +	     i++) {
> +		if (!present_section_nr(i))
> +			continue;
> +		if (section_count == 0)
> +			section_nr = i;
> +		section_count++;
>   	}
>   
> -	return ret;
> +	if (section_count == 0)
> +		return 0;
> +	ret = init_memory_block(&mem, __nr_to_section(section_nr), MEM_ONLINE);
> +	if (ret)
> +		return ret;
> +	mem->section_count = section_count;
> +	return 0;
>   }
>   
> +
>   /*
>    * need an interface for the VM to add new memory regions,
>    * but without onlining it.
> @@ -733,7 +732,6 @@ int __init memory_dev_init(void)
>   	int ret;
>   	int err;
>   	unsigned long block_sz;
> -	struct memory_block *mem = NULL;
>   
>   	ret = subsys_system_register(&memory_subsys, memory_root_attr_groups);
>   	if (ret)
> @@ -747,12 +745,8 @@ int __init memory_dev_init(void)
>   	 * during boot and have been initialized
>   	 */
>   	mutex_lock(&mem_sysfs_mutex);
> -	for (i = 0; i < NR_MEM_SECTIONS; i++) {
> -		if (!present_section_nr(i))
> -			continue;
> -		/* don't need to reuse memory_block if only one per block */
> -		err = add_memory_section(__nr_to_section(i),
> -				 (sections_per_block == 1) ? NULL : &mem);
> +	for (i = 0; i < NR_MEM_SECTIONS; i += sections_per_block) {

Why do you remove present_setcion_nr() check?

> +		err = add_memory_block(i);
>   		if (!ret)

Thanks,
Yasuaki Ishimatasu

>   			ret = err;
>   	}
> 

Re: [PATCH 7/7] drivers: base: refactor add_memory_section() to add_memory_block()

[Yasuaki Ishimatsu]

(2013/08/22 17:20), Yasuaki Ishimatsu wrote:
> (2013/08/21 2:13), Seth Jennings wrote:
>> Right now memory_dev_init() maintains the memory block pointer
>> between iterations of add_memory_section().  This is nasty.
>>
>> This patch refactors add_memory_section() to become add_memory_block().
>> The refactoring pulls the section scanning out of memory_dev_init()
>> and simplifies the signature.
>>
>> Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
>> ---
>>    drivers/base/memory.c | 48 +++++++++++++++++++++---------------------------
>>    1 file changed, 21 insertions(+), 27 deletions(-)
>>
>> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
>> index 7d9d3bc..021283a 100644
>> --- a/drivers/base/memory.c
>> +++ b/drivers/base/memory.c
>> @@ -602,32 +602,31 @@ static int init_memory_block(struct memory_block **memory,
>>    	return ret;
>>    }
>>    
>> -static int add_memory_section(struct mem_section *section,
>> -			struct memory_block **mem_p)
>> +static int add_memory_block(int base_section_nr)
>>    {
>> -	struct memory_block *mem = NULL;
>> -	int scn_nr = __section_nr(section);
>> -	int ret = 0;
>> -
>> -	if (mem_p && *mem_p) {
>> -		if (scn_nr >= (*mem_p)->start_section_nr &&
>> -		    scn_nr <= (*mem_p)->end_section_nr) {
>> -			mem = *mem_p;
>> -		}
>> -	}
>> +	struct memory_block *mem;
>> +	int i, ret, section_count = 0, section_nr;
>>    
>> -	if (mem)
>> -		mem->section_count++;
>> -	else {
>> -		ret = init_memory_block(&mem, section, MEM_ONLINE);
>> -		/* store memory_block pointer for next loop */
>> -		if (!ret && mem_p)
>> -			*mem_p = mem;
>> +	for (i = base_section_nr;
>> +	     (i < base_section_nr + sections_per_block) && i < NR_MEM_SECTIONS;
>> +	     i++) {
>> +		if (!present_section_nr(i))
>> +			continue;
>> +		if (section_count == 0)
>> +			section_nr = i;
>> +		section_count++;
>>    	}
>>    
>> -	return ret;
>> +	if (section_count == 0)
>> +		return 0;
>> +	ret = init_memory_block(&mem, __nr_to_section(section_nr), MEM_ONLINE);
>> +	if (ret)
>> +		return ret;
>> +	mem->section_count = section_count;
>> +	return 0;
>>    }
>>    
>> +
>>    /*
>>     * need an interface for the VM to add new memory regions,
>>     * but without onlining it.
>> @@ -733,7 +732,6 @@ int __init memory_dev_init(void)
>>    	int ret;
>>    	int err;
>>    	unsigned long block_sz;
>> -	struct memory_block *mem = NULL;
>>    
>>    	ret = subsys_system_register(&memory_subsys, memory_root_attr_groups);
>>    	if (ret)
>> @@ -747,12 +745,8 @@ int __init memory_dev_init(void)
>>    	 * during boot and have been initialized
>>    	 */
>>    	mutex_lock(&mem_sysfs_mutex);
>> -	for (i = 0; i < NR_MEM_SECTIONS; i++) {
>> -		if (!present_section_nr(i))
>> -			continue;
>> -		/* don't need to reuse memory_block if only one per block */
>> -		err = add_memory_section(__nr_to_section(i),
>> -				 (sections_per_block == 1) ? NULL : &mem);
>> +	for (i = 0; i < NR_MEM_SECTIONS; i += sections_per_block) {
> 
> Why do you remove present_setcion_nr() check?

Sorry for the noise. I understood.
The check was moved into add_memory_section(). So it was removed.

Thanks,
Yasuaki Ishimatsu

> 
>> +		err = add_memory_block(i);
>>    		if (!ret)
> 
> Thanks,
> Yasuaki Ishimatasu
> 
>>    			ret = err;
>>    	}
>>
> 
> 
> --
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Re: [PATCH 1/7] drivers: base: move mutex lock out of add_memory_section()

[Yasuaki Ishimatsu]

(2013/08/21 2:24), Seth Jennings wrote:
> Gah! Forgot the cover letter.
>
> This patchset just seeks to clean up and refactor some things in
> memory.c for better understanding and possibly better performance due do
> a decrease in mutex acquisitions and refcount churn at boot time.  No
> functional change is intended by this set!

All patches were
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Tested-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>

Thanks,
Yasuaki Ishimatsu

>
> Seth
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>