linux-kernel - Re: [PATCH mmotm 1/5] nilfs2: fix problems of memory allocation in ioctl

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Message-ID: <20081214151327.GM25779@one.firstfloor.org>
Date:	Sun, 14 Dec 2008 16:13:27 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>
Cc:	akpm@...ux-foundation.org, andi@...stfloor.org,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH mmotm 1/5] nilfs2: fix problems of memory allocation in ioctl

> -#define KMALLOC_SIZE_MIN	4096	/* 4KB */
> -#define KMALLOC_SIZE_MAX	131072	/* 128 KB */
> +#define NILFS_IOCTL_KMALLOC_SIZE	8192	/* 8KB */

Better would be if you could go to PAGE_SIZE. order 0 allocations
are typically the fastest / least likely to stall.

Also in this case it's a good idea to use __get_free_pages()
directly, kmalloc tends to be become less efficient at larger
sizes.

-Andi
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