https://bugs.dragonflybsd.org/https://bugs.dragonflybsd.org/favicon.ico?16293952082015-07-23T22:00:05ZDragonFlyBSD bugtrackerDragonFlyBSD - Bug #2828: On AMD APUs and Bulldozer CPUs, the machdep.cpu_idle_hlt sysctl should be 3 by defaulthttps://bugs.dragonflybsd.org/issues/2828?journal_id=126942015-07-23T22:00:05Zdillon
<ul></ul><p>Hmm. Did you measure the actual power consumption? The default (2) is supposed to be a hybrid approach that falls into ACPI. But looking at it, it is quite possible that the code in kern/lwkt_thread.c that is responsible for resetting gd_idle_repeat to 0 is breaking the concept.</p>
<p>-Matt</p> DragonFlyBSD - Bug #2828: On AMD APUs and Bulldozer CPUs, the machdep.cpu_idle_hlt sysctl should be 3 by defaulthttps://bugs.dragonflybsd.org/issues/2828?journal_id=126962015-07-24T00:30:56Ztautolog
<ul></ul><p>I helped measure this on my laptop with the author's kernel nodule. I got better cstate stats, and my cpu temp went from 97c to 70c during idle, but the actual battery life improvement was 1:40 instead of 1:30. My battery is capping out, so a new battery would probably get 20 extra minutes. </p>
<p>In my opinion, the much better heat profile of the laptop made it worth it alone, because that helped even when it was plugged in.</p>
<p>I can test whatever you need.</p>
<p>Ben<br /> Original Message <br />From: <a class="email" href="mailto:bugtracker-admin@leaf.dragonflybsd.org">bugtracker-admin@leaf.dragonflybsd.org</a><br />Sent: Thursday, July 23, 2015 3:02 PM<br />Reply To: <a class="email" href="mailto:bugs@dragonflybsd.org">bugs@dragonflybsd.org</a><br />Subject: [DragonFlyBSD - Bug <a class="issue tracker-1 status-1 priority-5 priority-high3" title="Bug: On AMD APUs and Bulldozer CPUs, the machdep.cpu_idle_hlt sysctl should be 3 by default (New)" href="https://bugs.dragonflybsd.org/issues/2828">#2828</a>] On AMD APUs and Bulldozer CPUs, the machdep.cpu_idle_hlt sysctl should be 3 by default</p>
<p>Issue <a class="issue tracker-1 status-1 priority-5 priority-high3" title="Bug: On AMD APUs and Bulldozer CPUs, the machdep.cpu_idle_hlt sysctl should be 3 by default (New)" href="https://bugs.dragonflybsd.org/issues/2828">#2828</a> has been updated by dillon.</p>
<p>Hmm. Did you measure the actual power consumption? The default (2) is supposed to be a hybrid approach that falls into ACPI. But looking at it, it is quite possible that the code in kern/lwkt_thread.c that is responsible for resetting gd_idle_repeat to 0 is breaking the concept.</p>
<p>-Matt</p>
<p>----------------------------------------<br />Bug <a class="issue tracker-1 status-1 priority-5 priority-high3" title="Bug: On AMD APUs and Bulldozer CPUs, the machdep.cpu_idle_hlt sysctl should be 3 by default (New)" href="https://bugs.dragonflybsd.org/issues/2828">#2828</a>: On AMD APUs and Bulldozer CPUs, the machdep.cpu_idle_hlt sysctl should be 3 by default<br /><a class="external" href="http://bugs.dragonflybsd.org/issues/2828#change-12694">http://bugs.dragonflybsd.org/issues/2828#change-12694</a></p>
<ul>
<li>Author: vadaszi</li>
<li>Status: New</li>
<li>Priority: High</li>
<li>Assignee: vadaszi</li>
<li>Category: Kernel</li>
<li>Target version: 4.2.x<br />----------------------------------------<br />Power usage of a default install is unnecessarily high on current AMD CPUs. Setting the default value of the machdep.cpu_idle_hlt sysctl on these CPUs to 3 by default allows for significant power savings.</li>
</ul>
<p>I'm not sure how setting machdep.cpu_idle_hlt=3 affects power usage on AMD Family 10h CPUs (e.g. Phenom CPUs).</p>
<p>Some quick benchmarking should be done if possible, to compare the performance difference.</p>
<p>-- <br />You have received this notification because you have either subscribed to it, or are involved in it.<br />To change your notification preferences, please click here: <a class="external" href="http://bugs.dragonflybsd.org/my/account">http://bugs.dragonflybsd.org/my/account</a></p> DragonFlyBSD - Bug #2828: On AMD APUs and Bulldozer CPUs, the machdep.cpu_idle_hlt sysctl should be 3 by defaulthttps://bugs.dragonflybsd.org/issues/2828?journal_id=140572021-05-11T11:07:27Ztuxillo
<ul><li><strong>Target version</strong> changed from <i>4.2</i> to <i>6.0</i></li></ul>