Re: [PATCH] mm/mmap.c: Remove redundant local variables for may_expand_vm()

[Chen Gang <xili_gchen_5257@hotmail.com>]

On 11/10/15 09:39, Naoya Horiguchi wrote:
> On Tue, Nov 10, 2015 at 05:41:08AM +0800, Chen Gang wrote:
>> diff --git a/mm/mmap.c b/mm/mmap.c
>> index 2ce04a6..a515260 100644
>> --- a/mm/mmap.c
>> +++ b/mm/mmap.c
>> @@ -2988,12 +2988,7 @@ out:
>>   */
>>  int may_expand_vm(struct mm_struct *mm, unsigned long npages)
> 
> marking inline? 
> 

For me, inline is OK. But I guess, it depends on the members tastes: "It
is used at 5 areas within mm, inline will expand the binary size".

>>  {
>> -	unsigned long cur = mm->total_vm;	/* pages */
>> -	unsigned long lim;
>> -
>> -	lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
>> -
>> -	if (cur + npages > lim)
>> +	if (mm->total_vm + npages > (rlimit(RLIMIT_AS) >> PAGE_SHIFT))
>>  		return 0;
>>  	return 1;
> 
> How about doing simply
> 
> 	return mm->total_vm + npages <= (rlimit(RLIMIT_AS) >> PAGE_SHIFT);
> 

For me, only one line is OK. But I guess, it also depends on the members
tastes: does it let code a little complex?

If we can use bool instead of int for may_epand_mm() return value, I
guess, one line implementation (your idea) will be OK to all members.

> ? These changes save some bytes :)
> 
>    text    data     bss     dec     hex filename 
>   20566    2250      40   22856    5948 mm/mmap.o (before)
> 
>    text    data     bss     dec     hex filename 
>   20542    2250      40   22832    5930 mm/mmap.o (after)
> 
> Thanks,
> Naoya Horiguchi
> 

Thanks.
-- 
Chen Gang (陈刚)

Open, share, and attitude like air, water, and life which God blessed

--
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>