Separate out the readahead/lookahead sizes limiting code,
and put them to stand-alone limit_rala() function.
Signed-off-by: Wu Fengguang <[email protected]>
---
--- linux-2.6.17-rc4-mm3.orig/mm/readahead.c
+++ linux-2.6.17-rc4-mm3/mm/readahead.c
@@ -1009,10 +1009,8 @@ static int ra_dispatch(struct file_ra_st
* - @la_size stores the look-ahead size of previous request.
*/
static int adjust_rala(unsigned long ra_max,
- unsigned long *ra_size, unsigned long *la_size)
+ unsigned long *ra_size, unsigned long *la_size)
{
- unsigned long stream_shift = *la_size;
-
/*
* Substract the old look-ahead to get real safe size for the next
* read-ahead request.
@@ -1029,8 +1027,16 @@ static int adjust_rala(unsigned long ra_
*/
*la_size = *ra_size / LOOKAHEAD_RATIO;
+ return 1;
+}
+
+static void limit_rala(unsigned long ra_max, unsigned long la_old,
+ unsigned long *ra_size, unsigned long *la_size)
+{
+ unsigned long stream_shift;
+
/*
- * Apply upper limits.
+ * Apply basic upper limits.
*/
if (*ra_size > ra_max)
*ra_size = ra_max;
@@ -1041,11 +1047,9 @@ static int adjust_rala(unsigned long ra_
* Make sure stream_shift is not too small.
* (So that the next global_shift will not be too small.)
*/
- stream_shift += (*ra_size - *la_size);
+ stream_shift = la_old + (*ra_size - *la_size);
if (stream_shift < *ra_size / 4)
*la_size -= (*ra_size / 4 - stream_shift);
-
- return 1;
}
/*
@@ -1117,13 +1121,13 @@ state_based_readahead(struct address_spa
struct page *page, pgoff_t index,
unsigned long req_size, unsigned long ra_max)
{
- unsigned long ra_old;
- unsigned long ra_size;
- unsigned long la_size;
+ unsigned long ra_old, ra_size;
+ unsigned long la_old, la_size;
unsigned long remain_space;
unsigned long growth_limit;
- la_size = ra->readahead_index - index;
+ la_old = la_size = ra->readahead_index - index;
+ ra_old = ra_readahead_size(ra);
ra_size = compute_thrashing_threshold(ra, &remain_space);
if (page && remain_space <= la_size && la_size > 1) {
@@ -1131,7 +1135,6 @@ state_based_readahead(struct address_spa
return 0;
}
- ra_old = ra_readahead_size(ra);
growth_limit = req_size;
growth_limit += ra_max / 16;
growth_limit += (2 + readahead_ratio / 64) * ra_old;
@@ -1141,6 +1144,8 @@ state_based_readahead(struct address_spa
if (!adjust_rala(growth_limit, &ra_size, &la_size))
return 0;
+ limit_rala(growth_limit, la_old, &ra_size, &la_size);
+
ra_set_class(ra, RA_CLASS_STATE);
ra_set_index(ra, index, ra->readahead_index);
ra_set_size(ra, ra_size, la_size);
--
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
