Re: [brokenpatch] page accounting

[Suparna Bhattacharya]

Andrew Morton wrote:
> 
> The patch implements per-CPU accounting of the global number
> of locked, diry and pagecache pages.
> 
> -#define PG_locked               0      /* Page is locked. Don't touch. */
> +
> +/*
> + * Don't use the *_dontuse flags.  Use the macros.  Otherwise
> + * you'll break locked- and dirty-page accounting.
> + */
> +#define PG_locked_dontuse       0      /* Page is locked. Don't touch. */
>  #define PG_error                1
>  #define PG_referenced           2
>  #define PG_uptodate             3
> -#define PG_dirty                4
> +#define PG_dirty_dontuse        4
>  #define PG_unused               5
>  #define PG_lru                  6
>  #define PG_active               7
> -#define PG_slab                         8
> -#define PG_skip                        10
> +#define PG_slab                         8      /* kill me if needed: slab debug */

A little plea for mercy for this tiny bit :)
Could we keep PG_slab around unless its really causing trouble ? It
makes life easier for some things we do ... Also its rather nice that
today as a result of a wide usage of
slab infrastructure in the kernel, one can easily/directly interpret the
contents of 
almost any arbitrary memory location in the kernel, if its a slab page,
as one knows what type of data it contains. 

> +#define PG_skip                        10      /* kill me now: obsolete */
>  #define PG_highmem             11
>  #define PG_checked             12      /* kill me in 2.5.<early>. */
>  #define PG_arch_1              13
>  #define PG_reserved            14
>  #define PG_launder             15      /* written out by VM pressure.. */
> -
>  #define PG_private             16      /* Has something at ->private */
>