From 2a09b333c3096cfb0d361a983a4c479c4d54ed09 Mon Sep 17 00:00:00 2001
From: Victor Lowther <victor.lowther@gmail.com>
Date: Sun, 29 Jun 2008 12:07:22 -0500
Subject: More comments to the power hooks.

Also added an environment variable that will (hopefully) tell us
what type of system we have.
---
 pm/pm-functions.in     | 6 ++++++
 pm/power.d/laptop-mode | 6 +++++-
 pm/power.d/readahead   | 3 +++
 pm/power.d/xfs_buffer  | 2 ++
 4 files changed, 16 insertions(+), 1 deletion(-)

(limited to 'pm')

diff --git a/pm/pm-functions.in b/pm/pm-functions.in
index 9a25b10..4ae6fc6 100644
--- a/pm/pm-functions.in
+++ b/pm/pm-functions.in
@@ -85,6 +85,12 @@ done
 
 . "${PM_FUNCTIONS}"
 
+if command_exists dmidecode; then
+    export CHASSIS_TYPE="$(dmidecode -s chassis-type)"
+else
+    export CHASSIS_TYPE=Unknown
+fi
+
 # Simple little logging function.
 # We do it this way because 'echo -n' is not posix.
 log()
diff --git a/pm/power.d/laptop-mode b/pm/power.d/laptop-mode
index 52a8452..aae2335 100644
--- a/pm/power.d/laptop-mode
+++ b/pm/power.d/laptop-mode
@@ -2,7 +2,11 @@
 
 VM="/proc/sys/vm"
 
-[ -f $VM/laptop_mode -a -f $VM/dirty_ratio ] || exit $NA
+[ -w $VM/laptop_mode -a -w $VM/dirty_ratio ] || exit $NA
+
+# We might only want to enable laptop mode on actual laptops.
+# It really depends on how green we want to try to make the Linux
+# world.  
 
 laptop_mode_ac() {
     # disable laptop mode, set vm parameters back to sane defaults
diff --git a/pm/power.d/readahead b/pm/power.d/readahead
index c61ce43..3636909 100644
--- a/pm/power.d/readahead
+++ b/pm/power.d/readahead
@@ -2,6 +2,9 @@
 
 [ -x /sbin/blockdev ] || exit $NA
 
+# more readahead = (hopefully) less hard drive activity.
+# less readahead = less trashing the page cache.
+
 readahead() {
     # the intent here is to iterate through all filesystems
     # mounted on a local block device. It Works For The Maintainer(tm).
diff --git a/pm/power.d/xfs_buffer b/pm/power.d/xfs_buffer
index ec8a248..3d32ee4 100644
--- a/pm/power.d/xfs_buffer
+++ b/pm/power.d/xfs_buffer
@@ -5,6 +5,8 @@
 XFS="/proc/sys/fs/xfs"
 [ -f $XFS/age_buffer_centisecs ] || exit $NA
 
+# Why does XFS have its own parameters instead of just using the
+# VM subsystem ones?  Only SGI knows...
 
 xfs_ac() {
     # don't buffer so much, flush data out regularly.
-- 
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