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SubjectRe: Slowwwwwwwwwwww NFS read performance....
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På to , 15/01/2004 klokka 15:16, skreiv Trond Myklebust:
> På to , 15/01/2004 klokka 14:53, skreiv Ram Pai:
> > Yes this problem has been reported earlier. Attaching Andrew's patch
> > that reverts a change. This should work. Please confirm.
>
> Sorry to disappoint you, but that change appears already in 2.6.1-mm3,
> and does not suffice to fix the problem.

The following reversion is what fixes my regression. That puts the
sequential read numbers back to the 2.6.0 values of ~140MB/sec (from the
current 2.6.1 values of 14MB/second)...

Cheers,
Trond

diff -u --recursive --new-file linux-2.6.1-mm3/mm/readahead.c linux-2.6.1-fixed/mm/readahead.c
--- linux-2.6.1-mm3/mm/readahead.c 2004-01-09 01:59:07.000000000 -0500
+++ linux-2.6.1-fixed/mm/readahead.c 2004-01-15 15:41:35.118000000 -0500
@@ -474,13 +474,9 @@
/*
* This read request is within the current window. It is time
* to submit I/O for the ahead window while the application is
- * about to step into the ahead window.
- * Heuristic: Defer reading the ahead window till we hit
- * the last page in the current window. (lazy readahead)
- * If we read in earlier we run the risk of wasting
- * the ahead window.
+ * crunching through the current window.
*/
- if (ra->ahead_start == 0 && offset == (ra->start + ra->size -1)) {
+ if (ra->ahead_start == 0) {
ra->ahead_start = ra->start + ra->size;
ra->ahead_size = ra->next_size;
actual = do_page_cache_readahead(mapping, filp,
-
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