Improve wording about Btrfs COW

[kernel-news-talk.git] / index.html

diff --git a/index.html b/index.html
index 68e0fe8758e490ef43e0eff170aae6764ea21ba5..31c5d34d1e27a5330b890a9513c964c6e4932350 100644 (file)
--- a/index.html
+++ b/index.html
@@ -155,7 +155,7 @@
       unnamed temporary file on that filesystem
     </li>
     <li>
-      As with <tt>tmpfile()</tt>, the file disppears on
+      As with <tt>tmpfile()</tt>, the file disappears on
       last <tt>close()</tt>
     </li>
     <li>
@@ -257,9 +257,12 @@
   <h1>Btrfs offline dedupe [3.12]</h1>
   <ul class="incremental">
     <li>
-      Btrfs generally does COW rather than updating in-place, allowing
-      snapshots and file copies to defer the actual copying and save
-      space
+      Btrfs generally copies and frees blocks, rather than updating
+      in-place
+    </li>
+    <li>
+      This allows snapshots and file copies to copy-by-reference,
+      deferring the real copying until changes are made
     </li>
     <li>
       Filesystems may still end up with multiple copies of the same
@@ -342,7 +345,7 @@
       but didn't support kernel running little-endian
     </li>
     <li>
-      Linux 3.13 added little-endian kernel suport, along with new
+      Linux 3.13 added little-endian kernel support, along with new
       userland ELF ABI variant - we call it ppc64el
     </li>
     <li>
@@ -379,6 +382,32 @@
   </ul>
 </div>
 
+<div class="slide">
+  <h1>Multiqueue block devices [3.16]</h1>
+  <ul class="incremental">
+    <li>
+      Each block device has a command queue (possibly shared with
+      other devices)
+    </li>
+    <li>
+      Queue may be partly implemented by hardware (NCQ) or only
+      in software
+    </li>
+    <li>
+      A single queue means initiation is serialised and completion
+      involves IPI - can be bottleneck for fast devices
+    </li>
+    <li>
+      High-end SSDs support multiple queues, but kernel needed changes
+      to use them
+    </li>
+    <li>
+      <tt>mtip32xx</tt> driver now supports multiqueue, but SCSI
+      drivers don't yet - may be backport-able?
+    </li>
+  </ul>
+</div>
+
 <div class="slide">
   <h1>Questions?</h1>
 </div>