From: Eric Dumazet <dada1@cosmosbay.com>
To: Vadim Lobanov <vlobanov@speakeasy.net>
Cc: akpm@osdl.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fdtable: Eradicate fdarray overflow.
Date: Thu, 12 Oct 2006 07:19:20 +0200 [thread overview]
Message-ID: <452DD058.7000301@cosmosbay.com> (raw)
In-Reply-To: <200610111958.03238.vlobanov@speakeasy.net>
Vadim Lobanov a écrit :
>
> diff -Npru old/fs/file.c new/fs/file.c
> --- old/fs/file.c 2006-10-10 18:58:21.000000000 -0700
> +++ new/fs/file.c 2006-10-11 19:37:23.000000000 -0700
> @@ -164,9 +164,8 @@ static struct fdtable * alloc_fdtable(un
> * the fdarray into page-sized chunks: starting at a quarter of a page,
> * and growing in powers of two from there on.
> */
> - nr++;
> nr /= (PAGE_SIZE / 4 / sizeof(struct file *));
> - nr = roundup_pow_of_two(nr);
> + nr = roundup_pow_of_two(nr + 1);
> nr *= (PAGE_SIZE / 4 / sizeof(struct file *));
> if (nr > NR_OPEN)
> nr = NR_OPEN;
Hi Vadim
I find your PAGE_SIZE/4 minimum allocation quite unjustified.
For architectures with 64K PAGE_SIZE, we endup allocating 16K, for poor tasks
that happen to touch a not so high (>= 64) file descriptor...
I would vote for a fixed size, like 1024
Eric
next prev parent reply other threads:[~2006-10-12 5:19 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-12 2:58 [PATCH] fdtable: Eradicate fdarray overflow Vadim Lobanov
2006-10-12 5:19 ` Eric Dumazet [this message]
2006-10-12 6:07 ` Vadim Lobanov
2006-10-12 6:32 ` Eric Dumazet
2006-10-12 7:16 ` Vadim Lobanov
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