Message-ID: <43872BF2.3030407@cosmosbay.com>
Date: Fri, 25 Nov 2005 16:21:22 +0100
From: Eric Dumazet <dada1@cosmosbay.com>
User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206)
MIME-Version: 1.0
To: Wu Fengguang <wfg@mail.ustc.edu.cn>
CC: linux-kernel@vger.kernel.org, Andrew Morton <akpm@osdl.org>
Subject: Re: [PATCH 10/19] readahead: state based method
References: <20051125151210.993109000@localhost.localdomain> <20051125151550.440541000@localhost.localdomain>
In-Reply-To: <20051125151550.440541000@localhost.localdomain>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1522
Lines: 42

Wu Fengguang a ?crit :

>  include/linux/fs.h |    8 +
> 
> --- linux-2.6.15-rc2-mm1.orig/include/linux/fs.h
> +++ linux-2.6.15-rc2-mm1/include/linux/fs.h
> @@ -604,13 +604,19 @@ struct file_ra_state {
>  	unsigned long start;		/* Current window */
>  	unsigned long size;
>  	unsigned long flags;		/* ra flags RA_FLAG_xxx*/
> -	unsigned long cache_hit;	/* cache hit count*/
> +	uint64_t      cache_hit;	/* cache hit count*/
>  	unsigned long prev_page;	/* Cache last read() position */
>  	unsigned long ahead_start;	/* Ahead window */
>  	unsigned long ahead_size;
>  	unsigned long ra_pages;		/* Maximum readahead window */
>  	unsigned long mmap_hit;		/* Cache hit stat for mmap accesses */
>  	unsigned long mmap_miss;	/* Cache miss stat for mmap accesses */
> +
> +	unsigned long age;
> +	pgoff_t la_index;
> +	pgoff_t ra_index;
> +	pgoff_t lookahead_index;
> +	pgoff_t readahead_index;
>  };

Hum... This sizeof(struct file) increase seems quite large...

Have you ever considered to change struct file so that file_ra_state is not 
embedded, but dynamically allocated (or other strategy) for regular files ?

I mean, sockets, pipes cannot readahead... And some machines use far more 
sockets than regular files.

I wrote such a patch in the past I could resend...

Eric
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/