X-Git-Url: http://git.tuebingen.mpg.de/?a=blobdiff_plain;f=LVM.m4;h=959d4cec09a9ca53ef395c7926880527d66c36aa;hb=be750347503fa460c4af938f5615d973abc8b7bc;hp=bf130769e1ccf4e73513c292de25f47bcc59ab32;hpb=b88565f31b0a7874e62a1dc9e97b9c944c11e41f;p=aple.git

diff --git a/LVM.m4 b/LVM.m4
index bf13076..959d4ce 100644
--- a/LVM.m4
+++ b/LVM.m4
@@ -60,21 +60,18 @@ they can be submitted as a unit for performance reasons. The thusly
 processed bios then form an I/O request which is handed to an <em>
 I/O scheduler </em> (also known as <em> elevator</em>). </p>
 
-<p> At this time of writing (2018-11) there exist two different sets
-of schedulers: the traditional single-queue schedulers and the
-modern multi-queue schedulers, which are expected to replace the
-single-queue schedulers soon. The three single-queue schedulers,
-noop, deadline and cfq (complete fair queueing), were designed for
-rotating disks. They reorder requests with the aim to minimize seek
-time. The newer multi-queue schedulers, mq-deadline, kyber, and bfq
-(budget fair queueing), aim to max out even the fastest devices. As
-implied by the name "multi-queue", they implement several request
-queues, the number of which depends on the hardware in use. This
-has become necessary because modern storage hardware allows multiple
-requests to be submitted in parallel from different CPUs. Moreover,
-with many CPUs the locking overhead required to put a request into
-a queue increases. Per-CPU queues allow for per-CPU locks, which
-decreases queue lock contention. </p>
+<p> Traditionally, the schedulers were designed for rotating disks.
+They implemented a single request queue and reordered the queued
+I/O requests with the aim to minimize disk seek times. The newer
+multi-queue schedulers mq-deadline, kyber, and bfq (budget fair
+queueing) aim to max out even the fastest devices. As implied by
+the name "multi-queue", they implement several request queues,
+the number of which depends on the hardware in use. This has become
+necessary because modern storage hardware allows multiple requests
+to be submitted in parallel from different CPUs. Moreover, with many
+CPUs the locking overhead required to put a request into a queue
+increases. Per-CPU queues allow for per-CPU locks, which decreases
+queue lock contention. </p>
 
 <p> We will take a look at some aspects of the Linux block layer and on
 the various I/O schedulers. An exercise on loop devices enables the
@@ -837,12 +834,12 @@ EXERCISES()
 	target_args</code>. Determine the correct values for the first three
 	arguments to encrypt <code> /dev/loop0</code>. </li>
 
-	<li> The <code> target_args </code> for the dm-crypt target are
-	of the form <code> cipher key iv_offset device offset</code>. To
-	encrypt <code> /dev/loop0 </code> with AES-256, <code> cipher </code>
-	is <code> aes</code>, device is <code> /dev/loop0 </code> and both
-	offsets are zero. Come up with an idea to create a 256 bit key from
-	a passphrase. </li>
+	<li> The <code>target_args</code> for the dm-crypt target are
+	of the form <code>cipher key iv_offset device offset</code>. To
+	encrypt <code>/dev/loop0</code> with AES-256, <code>cipher</code>
+	is <code>aes</code>, <code>device</code> is <code>/dev/loop0</code>
+	and both offsets are zero. Come up with an idea to create a 256 bit
+	key from a passphrase. </li>
 
 	<li> The <code> create </code> subcommand of <code> dmsetup(8)
 	</code> creates a device from the given table. Run a command of