linux-kernel - Performance drop on Baytrail with 4.5-rc2

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <alpine.LSU.2.11.1602012122530.9114@er-systems.de>
Date:	Mon, 1 Feb 2016 21:34:28 +0100 (CET)
From:	Thomas Voegtle <tv@...96.de>
To:	philippe.longepe@...el.com
cc:	linux-kernel@...r.kernel.org, stephane.gasparini@...el.com,
	rafael.j.wysocki@...el.com
Subject: Performance drop on Baytrail with 4.5-rc2

Hi,

I have a Celeron J1900 system (Asrock Q1900B-ITX) always running the
latest kernel.
Since running the 4.5-rc2 kernel I have a performance drop in a ffmpeg
benchmark compared to 4.4. Converting a piece of mpeg to mp4 (to
/dev/null).

4.1 made the benchmark in 74s, 4.4 in 75s and now the 4.5-rc2 in 80s.

As the benchmark is very stable in results I easily could bisest it down
to the commit:

commit e70eed2b64545ab5c9d2f4d43372d79762f1b985
Author: Philippe Longepe <philippe.longepe@...el.com>
Date:   Fri Dec 4 17:40:32 2015 +0100

     cpufreq: intel_pstate: Account for non C0 time

I can revert this commit on top on 4.5-rc2 (4 of 5 hunks) and then the
benchmark is down to 76s.

Was this intended to decrease energy consumption?

     Thomas