From 35b44f0b7fa7d6600c2e65bb4bdfaaa289154dea Mon Sep 17 00:00:00 2001
From: Jan Vcelak <jvcelak@redhat.com>
Date: Fri, 7 Jan 2011 17:00:22 +0100
Subject: [PATCH] udev: add rules for scheduler tuning

---
 udev/80-tuned-iosched.rules       | 14 +++++++++++++
 udev/80-tuned-mpath-iosched.rules |  9 ++++++++
 udev/tuned-mpath-iosched          | 34 +++++++++++++++++++++++++++++++
 3 files changed, 57 insertions(+)
 create mode 100644 udev/80-tuned-iosched.rules
 create mode 100644 udev/80-tuned-mpath-iosched.rules
 create mode 100755 udev/tuned-mpath-iosched

diff --git a/udev/80-tuned-iosched.rules b/udev/80-tuned-iosched.rules
new file mode 100644
index 0000000..163f240
--- /dev/null
+++ b/udev/80-tuned-iosched.rules
@@ -0,0 +1,14 @@
+#
+# CFQ's default tunings are geared towards slow SATA disks.  If we detect
+# anything else, we change the tunings to drive deeper queue depths and
+# keep the device busy.
+#
+SUBSYSTEM!="block", GOTO="end_iosched"
+KERNEL=="dm-*", GOTO="end_iosched"
+ENV{DEVTYPE}=="partition", GOTO="end_iosched"
+ACTION!="add|change", GOTO="end_iosched"
+ENV{ID_BUS}=="ata", GOTO="end_iosched"
+ATTR{queue/scheduler}!="*\[cfq\]", GOTO="end_iosched"
+ATTR{queue/iosched/slice_idle}="0"
+ATTR{queue/iosched/quantum}="32"
+LABEL="end_iosched"
diff --git a/udev/80-tuned-mpath-iosched.rules b/udev/80-tuned-mpath-iosched.rules
new file mode 100644
index 0000000..0d65806
--- /dev/null
+++ b/udev/80-tuned-mpath-iosched.rules
@@ -0,0 +1,9 @@
+SUBSYSTEM!="block", GOTO="end_mpath_iosched"
+ENV{DEVTYPE}=="partition", GOTO="end_mpath_iosched"
+KERNEL!="dm-*", GOTO="end_mpath_iosched"
+ACTION!="change", GOTO="end_mpath_iosched"
+ATTR{queue/scheduler}!="*\[cfq\]", GOTO="end_mpath_iosched"
+ENV{DM_UUID}!="mpath-?*", GOTO="end_mpath_iosched"
+ENV{DM_ACTION}=="PATH_FAILED", GOTO="end_mpath_iosched"
+RUN+="tuned-mpath-iosched.sh"
+LABEL="end_mpath_iosched"
diff --git a/udev/tuned-mpath-iosched b/udev/tuned-mpath-iosched
new file mode 100755
index 0000000..78445b5
--- /dev/null
+++ b/udev/tuned-mpath-iosched
@@ -0,0 +1,34 @@
+#!/bin/sh
+#
+# For the request-based multipath driver, the I/O scheduler runs on the
+# multipath device, not the underlying "slave" devices.  This script
+# checks the ID_BUS attribute for each of the slave devices.  If it finds
+# an ata device, it leaves the I/O scheduler tunings alone.  For any other
+# device, we tune the I/O scheduler to try to keep the device busy.
+#
+
+if [ -z "$DEVPATH" ]; then
+	logger "$0: DEVPATH is not set"
+	exit 1
+fi
+
+if [ ! -d /sys/${DEVPATH}/slaves ]; then
+	logger "$0: 'slaves' directory under '$DEVPATH' does not exist"
+	exit 1
+fi
+
+needs_tuning=1
+for slave in $(command ls /sys/${DEVPATH}/slaves/* 2>/dev/null); do
+	bus_type=$(/sbin/udevadm info --query=property --path=$slave | grep -m1 ID_BUS | cut -d= -2)
+	if [ "$bus_type" = "ata" ]; then
+		needs_tuning=0
+		break
+	fi
+done
+
+if [ $needs_tuning -eq 1 ]; then
+	echo 0 > /sys/${DEVPATH}/queue/iosched/slice_idle
+	echo 32 > /sys/${DEVPATH}/queue/iosched/quantum
+fi
+
+exit 0