Re: [PATCH] Adaptive read-ahead v4

[Jörn Engel]

On Sun, 16 October 2005 01:47:31 +0800, WU Fengguang wrote:
>
> @@ -131,6 +133,63 @@ struct page_state {
>  
>  	unsigned long pgrotated;	/* pages rotated to tail of the LRU */
>  	unsigned long nr_bounce;	/* pages for bounce buffers */
> +
> +	unsigned long cache_miss;	/* read cache misses */
> +	unsigned long readrandom;	/* random reads */
> +	unsigned long pgreadrandom;	/* random read pages */
> +	unsigned long readahead_rescue; /* read-aheads rescued*/
> +	unsigned long pgreadahead_rescue;
> +	unsigned long readahead_end;	/* read-aheads passed EOF */
> +
> +	unsigned long readahead;	/* read-aheads issued */
> +	unsigned long readahead_return;	/* look-ahead marks returned */
> +	unsigned long readahead_eof;	/* read-aheads stop at EOF */
> +	unsigned long pgreadahead;	/* read-ahead pages issued */
> +	unsigned long pgreadahead_hit;	/* read-ahead pages accessed */
> +	unsigned long pgreadahead_eof;
> +
> +	unsigned long ra_newfile;	/* read-ahead on start of file */
> +	unsigned long ra_newfile_return;
> +	unsigned long ra_newfile_eof;
> +	unsigned long pgra_newfile;
> +	unsigned long pgra_newfile_hit;
> +	unsigned long pgra_newfile_eof;
> +
> +	unsigned long ra_state;		/* state based read-ahead */
> +	unsigned long ra_state_return;
> +	unsigned long ra_state_eof;
> +	unsigned long pgra_state;
> +	unsigned long pgra_state_hit;
> +	unsigned long pgra_state_eof;
> +
> +	unsigned long ra_context;	/* context based read-ahead */
> +	unsigned long ra_context_return;
> +	unsigned long ra_context_eof;
> +	unsigned long pgra_context;
> +	unsigned long pgra_context_hit;
> +	unsigned long pgra_context_eof;
> +
> +	unsigned long ra_contexta;	/* accelerated context based read-ahead */
> +	unsigned long ra_contexta_return;
> +	unsigned long ra_contexta_eof;
> +	unsigned long pgra_contexta;
> +	unsigned long pgra_contexta_hit;
> +	unsigned long pgra_contexta_eof;
> +
> +	unsigned long ra_backward;	/* prefetch pages for backward reading */
> +	unsigned long ra_backward_return;
> +	unsigned long ra_backward_eof;
> +	unsigned long pgra_backward;
> +	unsigned long pgra_backward_hit;
> +	unsigned long pgra_backward_eof;
> +
> +	unsigned long ra_random;	/* read-ahead on seek-and-read-pages */
> +	unsigned long ra_random_return;
> +	unsigned long ra_random_eof;
> +	unsigned long pgra_random;
> +	unsigned long pgra_random_hit;
> +	unsigned long pgra_random_eof;
> +
>  };

Without actually understanding what you're doing, wouldn't a struct
for all those groups make sense?  I bet it can simplify the actual
code as well.

Jörn

-- 
When people work hard for you for a pat on the back, you've got
to give them that pat.
-- Robert Heinlein
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