From 8aae17379df8772e46b0f28fdb4d3e974f65ad54 Mon Sep 17 00:00:00 2001
From: Victor Lowther <victor.lowther@gmail.com>
Date: Sat, 28 Jun 2008 23:25:11 -0500
Subject: Added some explanatory comments to the power hooks.

---
 pm/power.d/laptop-mode | 3 +++
 pm/power.d/readahead   | 4 ++++
 pm/power.d/xfs_buffer  | 2 ++
 3 files changed, 9 insertions(+)

diff --git a/pm/power.d/laptop-mode b/pm/power.d/laptop-mode
index 0e35f67..52a8452 100644
--- a/pm/power.d/laptop-mode
+++ b/pm/power.d/laptop-mode
@@ -5,6 +5,7 @@ VM="/proc/sys/vm"
 [ -f $VM/laptop_mode -a -f $VM/dirty_ratio ] || exit $NA
 
 laptop_mode_ac() {
+    # disable laptop mode, set vm parameters back to sane defaults
     echo 0 >$VM/laptop_mode
     echo 5 >$VM/dirty_background_ratio
     echo 2999 >$VM/dirty_expire_centisecs
@@ -13,6 +14,8 @@ laptop_mode_ac() {
 }
 
 laptop_mode_battery() {
+    # enable laptop mode, set vm parameters to buffer as many writes as 
+    # possible.
     echo 1 >$VM/laptop_mode
     echo 1 >$VM/dirty_background_ratio
     echo 60000 >$VM/dirty_expire_centisecs
diff --git a/pm/power.d/readahead b/pm/power.d/readahead
index 4247217..c61ce43 100644
--- a/pm/power.d/readahead
+++ b/pm/power.d/readahead
@@ -3,6 +3,10 @@
 [ -x /sbin/blockdev ] || exit $NA
 
 readahead() {
+    # the intent here is to iterate through all filesystems
+    # mounted on a local block device. It Works For The Maintainer(tm).
+    # More sophistication in figuring out what exactly is a local block device
+    # would be welcome.
     for dev in $(awk '/^\/dev\// {print $1}'</etc/mtab); do
 	/sbin/blockdev --setfra $1 "$dev"
     done
diff --git a/pm/power.d/xfs_buffer b/pm/power.d/xfs_buffer
index 7510e68..ec8a248 100644
--- a/pm/power.d/xfs_buffer
+++ b/pm/power.d/xfs_buffer
@@ -7,12 +7,14 @@ XFS="/proc/sys/fs/xfs"
 
 
 xfs_ac() {
+    # don't buffer so much, flush data out regularly.
     echo 1500 >$XFS/age_buffer_centisecs
     echo 3000 >$XFS/xfssyncd_centisecs
     echo 100  >$XFS/xfsbufd_centisecs
 }
 
 xfs_battery() {
+    # buffer lots
     echo 60000 >$XFS/age_buffer_centisecs
     echo 60000 >$XFS/xfssyncd_centisecs
     echo 3000  >$XFS/xfsbufd_centisecs
-- 
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