Re: [PATCH 14/33] readahead: state based method - data structure

[Wu Fengguang <wfg@mail.ustc.edu.cn>]

On Fri, May 26, 2006 at 10:05:52AM -0700, Andrew Morton wrote:
> Wu Fengguang <wfg@mail.ustc.edu.cn> wrote:
> >
> >  #define RA_FLAG_MISS 0x01	/* a cache miss occured against this file */
> >   #define RA_FLAG_INCACHE 0x02	/* file is already in cache */
> >  +#define RA_FLAG_MMAP		(1UL<<31)	/* mmaped page access */
> >  +#define RA_FLAG_NO_LOOKAHEAD	(1UL<<30)	/* disable look-ahead */
> >  +#define RA_FLAG_EOF		(1UL<<29)	/* readahead hits EOF */
> 
> Odd.  Why not use 4, 8, 16?

I'm now settled with:

-#define RA_FLAG_MISS 0x01      /* a cache miss occured against this file */
-#define RA_FLAG_INCACHE 0x02   /* file is already in cache */
+#define RA_FLAG_MISS   (1UL<<31) /* a cache miss occured against this file */
+#define RA_FLAG_INCACHE        (1UL<<30) /* file is already in cache */
+#define RA_FLAG_MMAP           (1UL<<29) /* mmaped page access */
+#define RA_FLAG_NO_LOOKAHEAD   (1UL<<28) /* disable look-ahead */
+#define RA_FLAG_EOF            (1UL<<27) /* readahead hits EOF */

And still let the low bits hold ra_class values.
-
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