lkml.org 
[lkml]   [2006]   [May]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[PATCH 08/32] readahead: {MIN,MAX}_RA_PAGES
    Define two convenient macros for read-ahead:
    - MAX_RA_PAGES: rounded down counterpart of VM_MAX_READAHEAD
    - MIN_RA_PAGES: rounded _up_ counterpart of VM_MIN_READAHEAD

    Note that the rounded up MIN_RA_PAGES will work flawlessly with _large_
    page sizes like 64k.

    Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn>
    ---

    mm/readahead.c | 12 ++++++++++--
    1 files changed, 10 insertions(+), 2 deletions(-)

    --- linux-2.6.17-rc4-mm3.orig/mm/readahead.c
    +++ linux-2.6.17-rc4-mm3/mm/readahead.c
    @@ -17,13 +17,21 @@
    #include <linux/backing-dev.h>
    #include <linux/pagevec.h>

    +/*
    + * Convienent macros for min/max read-ahead pages.
    + * Note that MAX_RA_PAGES is rounded down, while MIN_RA_PAGES is rounded up.
    + * The latter is necessary for systems with large page size(i.e. 64k).
    + */
    +#define MAX_RA_PAGES (VM_MAX_READAHEAD*1024 / PAGE_CACHE_SIZE)
    +#define MIN_RA_PAGES DIV_ROUND_UP(VM_MIN_READAHEAD*1024, PAGE_CACHE_SIZE)
    +
    void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
    {
    }
    EXPORT_SYMBOL(default_unplug_io_fn);

    struct backing_dev_info default_backing_dev_info = {
    - .ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE,
    + .ra_pages = MAX_RA_PAGES,
    .state = 0,
    .capabilities = BDI_CAP_MAP_COPY,
    .unplug_io_fn = default_unplug_io_fn,
    @@ -52,7 +60,7 @@ static inline unsigned long get_max_read

    static inline unsigned long get_min_readahead(struct file_ra_state *ra)
    {
    - return (VM_MIN_READAHEAD * 1024) / PAGE_CACHE_SIZE;
    + return MIN_RA_PAGES;
    }

    static inline void reset_ahead_window(struct file_ra_state *ra)
    --
    -
    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/

    \
     
     \ /
      Last update: 2006-05-27 17:55    [W:0.020 / U:0.360 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site