<p>This patch adds a new macro that has rpm call fsync() before each close(). The<br>
feature is off by default since most people will not want this, and is turned<br>
on either with a macro or command-line flag.</p>
<p>There are a few reasons for wanting this:</p>
<ol>
<li>
<p>To ensure that an RPM installation never fulls IO queues so much that<br>
the production workload has to wait for it to be flushed when calling sync()<br>
(think of databases)</p>
</li>
<li>
<p>For systems with very large numbers of disks to limit the amount of diskcache<br>
an RPM installation can cause eviction of to limit IO thrash.</p>
</li>
</ol>
<p>At Facebook, for the described workloads, we've found significant improvement on<br>
our IO load when turning on this feature. Exact numbers are a bit hard to<br>
quantify, but we are working on them. We see less threads of production<br>
databases stacking up when yum/rpm/dnf are running, for example.</p>
<p>One word of caution: this will give good results on SSDs, but using this on<br>
rotational disks won't make you happy.</p>

<hr>

<h4>You can view, comment on, or merge this pull request online at:</h4>
<p>  <a href='https://github.com/rpm-software-management/rpm/pull/187'>https://github.com/rpm-software-management/rpm/pull/187</a></p>

<h4>Commit Summary</h4>
<ul>
  <li>Add macro to force fsync() on close()</li>
</ul>

<h4>File Changes</h4>
<ul>
  <li>
    <strong>M</strong>
    <a href="https://github.com/rpm-software-management/rpm/pull/187/files#diff-0">lib/fsm.c</a>
    (4)
  </li>
  <li>
    <strong>M</strong>
    <a href="https://github.com/rpm-software-management/rpm/pull/187/files#diff-1">rpmio/rpmio.c</a>
    (22)
  </li>
  <li>
    <strong>M</strong>
    <a href="https://github.com/rpm-software-management/rpm/pull/187/files#diff-2">rpmio/rpmio.h</a>
    (7)
  </li>
  <li>
    <strong>M</strong>
    <a href="https://github.com/rpm-software-management/rpm/pull/187/files#diff-3">rpmpopt.in</a>
    (2)
  </li>
</ul>

<h4>Patch Links:</h4>
<ul>
  <li><a href='https://github.com/rpm-software-management/rpm/pull/187.patch'>https://github.com/rpm-software-management/rpm/pull/187.patch</a></li>
  <li><a href='https://github.com/rpm-software-management/rpm/pull/187.diff'>https://github.com/rpm-software-management/rpm/pull/187.diff</a></li>
</ul>

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