Index: chap-tuning.xml
===================================================================
RCS file: /cvsroot/htdocs/guide/en/chap-tuning.xml,v
retrieving revision 1.12
diff -b -u -r1.12 chap-tuning.xml
--- chap-tuning.xml 4 Apr 2007 08:08:05 -0000 1.12
+++ chap-tuning.xml 7 Apr 2007 10:15:17 -0000
@@ -1689,12 +1689,45 @@
LFS writes data to disk in a way that is sometimes too
- aggressive and leads to congestion.
- Information on how to throttle writing and finding the right
- parameters are available
- this and
- this mail.
+ aggressive and leads to congestion. Blair Sadewitz has described
+ a good method for throttling writing and finding the right
+ parameters
+
+ See
+ and
+ .
+ .
+ The first step is to disable the sync delay, by setting the
+ following tunables through &man.sysctl.8;:
+
+
+
+vfs.sync.delay = 0
+vfs.sync.filedelay = 0
+vfs.sync.metadelay = 0
+vfs.sync dirdelay = 0
+
+
+
+ Then, find out how much bandwidth you have inside and outside
+ of the disk. This can be done by running
+ newfs_lfs -ANF on a partition close to
+ cylinder 0, and then on a partition close to the last cyclinder.
+ Average these two numbers, and calculate the LFS
+ page trip with the following formula:
+
+
+
+ t = (avg_bandwidth_in_bytes / PAGE_SIZE) / 4
+
+
+
+ Now you can set the vfs.lfs.pagetrip tunable
+ to t through &man.sysctl.8;.
+
+
+