lkml.org 
[lkml]   [2005]   [Jan]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 3/4] cleanup ahead window calculation
    Not sure how much better this is, but it doesn't hurt anything.

    Steve

    Oleg Nesterov wrote:

    >This patch moves some code into the get_next_ra_size()
    >and renames it into 'set_next_ahead_window'.
    >
    >Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
    >
    >--- 2.6.11-rc2/mm/readahead.c~ 2005-01-25 15:17:13.000000000 +0300
    >+++ 2.6.11-rc2/mm/readahead.c 2005-01-25 16:51:50.000000000 +0300
    >@@ -85,20 +85,23 @@ static unsigned long get_init_ra_size(un
    > * not for each call to readahead. If a cache miss occured, reduce next I/O
    > * size, else increase depending on how close to max we are.
    > */
    >-static unsigned long get_next_ra_size(unsigned long cur, unsigned long max,
    >- unsigned long min, unsigned long * flags)
    >+static void set_next_ahead_window(struct file_ra_state *ra,
    >+ unsigned long max, unsigned long min)
    > {
    > unsigned long newsize;
    >+ unsigned long cur = ra->size;
    >
    >- if (*flags & RA_FLAG_MISS) {
    >+ ra->ahead_start = ra->start + cur;
    >+
    >+ if (ra->flags & RA_FLAG_MISS) {
    >+ ra->flags &= ~RA_FLAG_MISS;
    > newsize = max((cur - 2), min);
    >- *flags &= ~RA_FLAG_MISS;
    >- } else if (cur < max / 16) {
    >+ } else if (cur < max / 16)
    > newsize = 4 * cur;
    >- } else {
    >+ else
    > newsize = 2 * cur;
    >- }
    >- return min(newsize, max);
    >+
    >+ ra->ahead_size = min(newsize, max);
    > }
    >
    > #define list_to_page(head) (list_entry((head)->prev, struct page, lru))
    >@@ -457,9 +460,7 @@ page_cache_readahead(struct address_spac
    > * immediately.
    > */
    > if (req_size >= max) {
    >- ra->ahead_size = get_next_ra_size(ra->size, max, min,
    >- &ra->flags);
    >- ra->ahead_start = ra->start + ra->size;
    >+ set_next_ahead_window(ra, max, min);
    > blockable_page_cache_readahead(mapping, filp,
    > ra->ahead_start, ra->ahead_size, ra, 1);
    > }
    >@@ -497,9 +498,7 @@ page_cache_readahead(struct address_spac
    > ra->size = ra->ahead_size;
    > }
    >
    >- ra->ahead_size = get_next_ra_size(ra->size, max, min,
    >- &ra->flags);
    >- ra->ahead_start = ra->start + ra->size;
    >+ set_next_ahead_window(ra, max, min);
    >
    > block = ((offset + newsize - 1) >= ra->ahead_start);
    > if (!blockable_page_cache_readahead(mapping, filp,
    >
    >

    -
    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: 2005-03-22 14:09    [W:0.027 / U:148.660 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site