From c9fe94717598b48c3d34bf42d051b76e2189ef76 Mon Sep 17 00:00:00 2001
From: wangdi <wangdi>
Date: Fri, 27 Jun 2008 17:28:18 +0000
Subject: [PATCH] Branch:b1_6 missing stride_start_offset in stride-read-ahead.
b=16172 i=Oleg,Johann
---
lustre/ChangeLog | 9 +++++++++
lustre/llite/rw.c | 15 ++++++++-------
2 files changed, 17 insertions(+), 7 deletions(-)
diff --git a/lustre/ChangeLog b/lustre/ChangeLog
index bd26bb7022..8f18e9d6f3 100644
--- a/lustre/ChangeLog
+++ b/lustre/ChangeLog
@@ -182,6 +182,15 @@ Description: ldiskfs error: XXX blocks in bitmap, YYY in gd
Details : If blocks per group is less than blocksize*8, set rest of the
bitmap to 1.
+Severity : major
+Frequency : Application do stride read on lustre
+Bugzilla : 16172
+Description: The read performance will drop a lot if the application does
+ stride read.
+Details : Because the stride_start_offset are missing in stride read-ahead,
+ it will cause clients read a lot of unused pages in read-ahead,
+ then the read-performance drops.
+
-------------------------------------------------------------------------------
diff --git a/lustre/llite/rw.c b/lustre/llite/rw.c
index b29cbf83d8..2e6a71ffdb 100644
--- a/lustre/llite/rw.c
+++ b/lustre/llite/rw.c
@@ -1381,13 +1381,14 @@ static int ll_readahead(struct ll_readahead_state *ras,
ras->ras_next_readahead = max(end, end + 1);
RAS_CDEBUG(ras);
}
- ria.ria_start = start;
- ria.ria_end = end;
- /* If stride I/O mode is detected, get stride window*/
- if (stride_io_mode(ras)) {
- ria.ria_length = ras->ras_stride_length;
- ria.ria_pages = ras->ras_stride_pages;
- }
+ ria.ria_start = start;
+ ria.ria_end = end;
+ /* If stride I/O mode is detected, get stride window*/
+ if (stride_io_mode(ras)) {
+ ria.ria_stoff = ras->ras_stride_offset;
+ ria.ria_length = ras->ras_stride_length;
+ ria.ria_pages = ras->ras_stride_pages;
+ }
spin_unlock(&ras->ras_lock);
if (end == 0) {
--
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