linux-kernel - Re: [PATCH 1/3] xvmalloc memory allocator

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Date:	Sun, 29 Mar 2009 16:53:22 +0530
From:	Nitin Gupta <nitingupta910@...il.com>
To:	Marcin Slusarz <marcin.slusarz@...il.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Pekka Enberg <penberg@...helsinki.fi>,
	Ed Tomlinson <edt@....ca>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] xvmalloc memory allocator

Marcin Slusarz wrote:
> Nitin Gupta wrote:
>> +static void stat_inc(u64 *value)
>> +{
>> +    (*value)++;
>> +}
>> +
>> +static void stat_dec(u64 *value)
>> +{
>> +    (*value)--;
>> +}
> 
> Why not open code it?
>


This looks nicer, doesn't it?


>> +
>> +static u32 test_flag(struct block_header *block, enum blockflags flag)
>> +{
>> +    return block->prev & (1 << flag);
>> +}
>> +
>> +static void set_flag(struct block_header *block, enum blockflags flag)
>> +{
>> +    block->prev |= (1 << flag);
>> +}
>> +
>> +static void clear_flag(struct block_header *block, enum blockflags flag)
>> +{
>> +    block->prev &= ~(1 << flag);
>> +}
> 
> Why don't you use test_bit / __set_bit / __clear_bit directly?
> 

block->prev is 16 bits. __set_bit() etc. need unsigned long pointer.

>> +struct xv_pool *xv_create_pool(void)
>> +{
>> +    int i;
>> +    u32 ovhd_size;
>> +    struct xv_pool *pool;
>> +
>> +    ovhd_size = roundup(sizeof(*pool), PAGE_SIZE);
>> +    pool = kmalloc(ovhd_size, GFP_KERNEL);
>> +    if (!pool)
>> +        return NULL;
>> +
>> +    memset(pool, 0, ovhd_size);
> 
> Please use kzalloc.
> 

Ok...

>> +
>> +    for (i = 0; i < NUM_FREE_LISTS; i++) {
>> +        pool->freelist[i].pagenum = 0;
>> +        pool->freelist[i].offset = 0;
>> +    }
> 
> It was already zeroed by memset.
> 
Remains from earlier code; we used to set it to 'INVALID_PGNUM'.
Ok, will remove this.


Thanks for review.
Nitin
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