ra_min/ra_max are not initialized, fix it.
New benchmark numbers on
hda: ST3250820A, ATA DISK drive
hda: max request size: 512KiB
hda: 488397168 sectors (250059 MB) w/8192KiB Cache, CHS=30401/255/63, UDMA(100)
with nfs mount
mount -o tcp,rsize=$((rsize<<10)) localhost:$EXPORT $MNT
rsize stock adaptive
==================================
f
8k 3.07 2.51 -18.2%
32k 2.40 2.17 -9.6%
128k 2.40 2.35 -2.1%
ff
8k 12.44 6.40 -48.6%
32k 14.62 5.46 -62.7%
128k 15.79 5.19 -67.1%
d
8k 2.84 2.48 -12.7%
32k 2.53 1.99 -21.3%
128k 2.18 2.00 -8.3%
dd
8k 8.16 7.99 -2.1%
32k 8.27 6.88 -16.8%
128k 7.75 6.97 -10.1%
The 4 patterns tested are:
f: single file read
ff: double file parallel read
d: single dir read
dd: double dir parallel read
Signed-off-by: Fengguang Wu <[email protected]>
---
--- linux-2.6.19-rc6-mm1.orig/mm/readahead.c
+++ linux-2.6.19-rc6-mm1/mm/readahead.c
@@ -1616,6 +1616,10 @@ page_cache_readahead_adaptive(struct add
unsigned long ra_max;
int ret;
+ /* no read-ahead */
+ if (!ra->ra_pages)
+ return 0;
+
if (page) {
ClearPageReadahead(page);
@@ -1635,9 +1639,6 @@ page_cache_readahead_adaptive(struct add
offset + LAPTOP_POLL_INTERVAL))
return 0;
}
- } else if (ra->flags & RA_FLAG_NFSD) { /* nfsd read */
- ra_size = max_sane_readahead(req_size);
- goto readit;
}
if (page)
@@ -1647,11 +1648,13 @@ page_cache_readahead_adaptive(struct add
get_readahead_bounds(ra, &ra_min, &ra_max);
- /* read-ahead disabled? */
- if (unlikely(!ra_max || !readahead_ratio)) {
- ra_size = max_sane_readahead(req_size);
+ /* read as is */
+ if (!readahead_ratio)
+ goto readit;
+
+ /* nfsd read */
+ if (!page && (ra->flags & RA_FLAG_NFSD))
goto readit;
- }
/*
* Start of file.
@@ -1698,11 +1701,11 @@ page_cache_readahead_adaptive(struct add
return 0;
}
+readit:
/*
* Random read.
*/
ra_size = min(req_size, ra_max);
-readit:
ra_size = __do_page_cache_readahead(mapping, filp, offset, ra_size, 0);
ra_account(ra, RA_EVENT_RANDOM_READ, ra_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]
