Remove readahead_ratio from the growth_limit computing in state based method.
It simplifies the size ramp up rules to:
ahead_window_size = request_size +
current_window_size * 2 +
readahead_max / 16;
The first two sizes are apparent. The last one has two effects:
1) Ensure that we get acceptable readahead size in early start up phase.
It is an analog to the old 'first x4 then x2' trick.
2) Ensure that we reach readahead_max within 8 steps.
It is good for the laptop mode. A user may set a huge readahead_max, and
expect the kernel to do large I/Os right away.
Signed-off-by: Fengguang Wu <[EMAIL PROTECTED]>
---
mm/readahead.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- linux-2.6.21-rc3-mm2.orig/mm/readahead.c
+++ linux-2.6.21-rc3-mm2/mm/readahead.c
@@ -1099,7 +1099,7 @@ state_based_readahead(struct address_spa
growth_limit = req_size;
growth_limit += ra_max / 16;
- growth_limit += (2 + readahead_ratio / 64) * ra_old;
+ growth_limit += 2 * ra_old;
if (growth_limit > ra_max)
growth_limit = ra_max;
--
-
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