From 5707bfdf0aac985e8e82c9a5004eb458d1d79801 Mon Sep 17 00:00:00 2001 From: =?utf-8?q?Dan=20Hor=C3=A1k?= Date: Fri, 30 Oct 2009 11:23:08 +0100 Subject: [PATCH] update readahead value for better performance Description: dasd,zfcp: Add udev rule to set increased "default max readahead" Symptom: Sequential read performance on disks is not as good as it could be. Problem: The current "default max readahead" defined by the kernel is too small for s390 (128 kb). Solution: Add udev rule to set a better default value (512 kb). This will increase sequential read performance up to 40%. --- etc/udev/rules.d/60-readahead.rules | 13 +++++++++++++ 1 files changed, 13 insertions(+), 0 deletions(-) create mode 100644 etc/udev/rules.d/60-readahead.rules diff --git a/etc/udev/rules.d/60-readahead.rules b/etc/udev/rules.d/60-readahead.rules new file mode 100644 index 0000000..3133c66 --- /dev/null +++ b/etc/udev/rules.d/60-readahead.rules @@ -0,0 +1,13 @@ +# +# Rules to set an increased default max readahead size for s390 disk devices +# This file should be installed in /etc/udev/rules.d +# + +SUBSYSTEM!="block", GOTO="ra_end" + +ACTION!="add", GOTO="ra_end" +# on device add set initial readahead to 512 (instead of in kernel 128) +KERNEL=="sd*[!0-9]", ATTR{queue/read_ahead_kb}="512" +KERNEL=="dasd*[!0-9]", ATTR{queue/read_ahead_kb}="512" + +LABEL="ra_end" -- 1.6.3.3