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>
<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
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
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>
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>
</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>