X-Git-Url: https://git.decadent.org.uk/gitweb/?a=blobdiff_plain;ds=sidebyside;f=index.html;h=8408414c64d72ac5361560866e94d506202cb244;hb=refs%2Ftags%2Fcambridge-minidebconf-2014;hp=9e99a51a015bd62246401b74a3fc0340fd41ac61;hpb=61fa05974dac42b20d57f734218f5725dc66abdc;p=kernel-news-talk.git

diff --git a/index.html b/index.html
index 9e99a51..8408414 100644
--- 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
@@ -284,12 +287,11 @@
       and ebtables
     </li>
     <li>
-      All require a specific kernel module for each type of match
-      and each possible action
+      All limited to single protocol, and need a kernel module for
+      each match type and each action
     </li>
     <li>
-      Userland could only use the four protocol-specific APIs,
-      although the internal netfilter API is more flexible
+      Kernel's internal netfilter API is more flexible
     </li>
     <li>
       nftables exposes more of this flexibility, allowing userland
@@ -299,7 +301,7 @@
       nftables userland tool uses this API and is already packaged
     </li>
     <li>
-      Eventually, the old APIs will be removed and the old userland
+      Eventually, old APIs will be removed and old userland
       tools must be ported to use nftables
     </li>
   </ul>
@@ -343,7 +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>
@@ -380,6 +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>nvme</tt> and <tt>mtip32xx</tt> drivers now support
+      multiqueue, but SCSI drivers don't yet - may be backport-able?
+    </li>
+  </ul>
+</div>
+
 <div class="slide">
   <h1>Questions?</h1>
 </div>